ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Wed, 19 Jun 2019 13:27:11 GMT2019-06-19T13:27:11Z502161- Topology-induced thermal rectification in carbon nanodevicehttps://scholarbank.nus.edu.sg/handle/10635/98425Title: Topology-induced thermal rectification in carbon nanodevice
Authors: Jiang, J.W.; Wang, J.S.; Li, B.
Abstract: The thermal rectification (TR) effect in a topological system, Möbius graphene strip, is studied by nonequilibrium molecular-dynamics simulation with Nóse-Hoover heat baths. Due to the nonlinear interaction in graphene and the topological asymmetry of the Möbius strip, the TR phenomenon emerges and the value of TR can be as large as 120%. This topology-induced TR is not very sensitive to the temperature and size of the system; while the position of heat bath is important, since it can induce additional asymmetry. © 2010 EPLA.
Fri, 01 Jan 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/984252010-01-01T00:00:00Z
- General initial value form of the semiclassical propagatorhttps://scholarbank.nus.edu.sg/handle/10635/114334Title: General initial value form of the semiclassical propagator
Authors: Hu, B.; Jie, Q.; Li, B.; Wang, S.
Abstract: An idea similar to the block approach used to calculate the path integral of a quantum propagator was employed to obtain a general initial value form of the semiclassical propagator. The semiclassical propagator formulation involves only nearby orbit approximation. The simple initial value form of the semiclassical propagator is nonsingular everywhere is efficient for numeric implementation. A generalized formulation is obtained with the block idea. The initial value form maintains the accuracy with a properly specified weight function.
Sun, 01 Apr 2001 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1143342001-04-01T00:00:00Z
- Disturbance spreading in incommensurate and quasiperiodic systemshttps://scholarbank.nus.edu.sg/handle/10635/96257Title: Disturbance spreading in incommensurate and quasiperiodic systems
Authors: Hu, B.; Li, B.; Tong, P.
Abstract: The propagation of an initially localized excitation in one-dimensional incommensurate, quasiperiodic and random systems is investigated numerically. It is discovered that the time evolution of variances σ2(t) of atom displacements depends on the initial condition. For the initial condition with nonzero momentum, σ2(t) goes as tα with α=1 and 0 for incommensurate Frenkel-Kontorova model at V below and above Vc respectively, and α=1 for uniform, quasiperiodic and random chains. It is also found that α=1-β with β the exponent of distribution function of frequency at zero frequency, i.e., ρ(ω)∼ωβ (as ω→0). For the initial condition with zero momentum, α=0 for all systems studied. The underlying physical meaning of this diffusive behavior is discussed. ©2000 The American Physical Society.
Sat, 01 Apr 2000 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/962572000-04-01T00:00:00Z
- Bipolaron dynamics in non-degenerate polymershttps://scholarbank.nus.edu.sg/handle/10635/98644Title: Bipolaron dynamics in non-degenerate polymers
Authors: Yan, Y.-H.; Wu, C.-Q.; Li, B.-W.
Abstract: Bipolaron dynamics in non-degenerate polymers are discussed using the nonadiabatic dynamic method. First, charge injection process from metal electrode to a nondegenerate polymer in a metal/polymer/metal structure has been investigated. We demonstrate that the dynamical formation of a bipolaron sensitively depends on the work function of metal electrode. We also study the bipolaron dissociation process. It is found that the electric field that can dissociate the bipoalron is up to 106 V/cm, which is consistent with experiments. © World Scientific Publishing Company.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/986442007-09-30T00:00:00Z
- Anomalous heat conduction and anomalous diffusion in one-dimensional systemshttps://scholarbank.nus.edu.sg/handle/10635/116230Title: Anomalous heat conduction and anomalous diffusion in one-dimensional systems
Authors: Li, B.; Wang, J.
Abstract: A connection between anomalous heat conduction and anomalous diffusion in 1D systems was established. The central result includes all possible cases observed in different classes of 1D models, ranging from sub diffusion, normal diffusion, and superdiffusion to ballistic transport.
Fri, 25 Jul 2003 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1162302003-07-25T00:00:00Z
- Heat switch and modulator: A model of thermal transistorhttps://scholarbank.nus.edu.sg/handle/10635/98735Title: Heat switch and modulator: A model of thermal transistor
Authors: Wang, L.; Li, B.
Abstract: A model of a thermal transistor to control heat flow is reported. Like its electronic counterpart, the thermal transistor is a three-terminal device with the important feature that the heat current through two terminals can be switched or modulated by the temperature of the third terminal. The thermal transistor model is possible because of the negative differential thermal resistance. © World Scientific Publishing Company.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/987352007-09-30T00:00:00Z
- Heat conductivity in linear mixing systemshttps://scholarbank.nus.edu.sg/handle/10635/116383Title: Heat conductivity in linear mixing systems
Authors: Li, B.; Casati, G.; Wang, J.
Abstract: A study of heat conductivity in linear mixing system was carried out. A quasi-one-dimensional channel with triangular scatterers with internal angles was also investigated. The numerical value of the thermal conductivity computed via a Green-Kubo approach agrees with that obtained by direct numerical simulations with thermal baths.
Sat, 01 Feb 2003 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1163832003-02-01T00:00:00Z
- Size-dependent melting temperature and thermal conductivity of nanoscale semiconductorshttps://scholarbank.nus.edu.sg/handle/10635/98882Title: Size-dependent melting temperature and thermal conductivity of nanoscale semiconductors
Authors: Liang, L.H.; Li, B.
Abstract: A model describing size-dependent melting temperature and thermal conductivity of nanosemiconductors is proposed based on Lindermann's melting criterion and Debye model. By the atomic thermal vibration consideration and by introducing intrinsic size effect of phonon velocity and mean free path combined with surface scattering effect, the model predicts that the melting temperature and thermal conductivity of nanosemiconductors decrease as the size reduces. The size effect depends on such material parameters as the vibration entropy, mean free path, the characteristic crystal size and surface roughness. The predictions are in agreement with experimental results of Si nanoparticles, nanowires and thin films. © World Scientific Publishing Company.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/988822007-09-30T00:00:00Z
- Anomalous Thermal Transport in Nanostructureshttps://scholarbank.nus.edu.sg/handle/10635/98966Title: Anomalous Thermal Transport in Nanostructures
Authors: Zhang, G.; Liu, S.; Li, B.
Abstract: Thermal transport in nanoscale structures has attracted an increasing attention in the past two decades. Here we give a brief overview of the recent developments in experimental and theoretical studies of heat transport in nanomaterials such as nanotubes and nanowires. In particular, we will demonstrate that the phonons in nanotubes and nanowires transport superdiffusively, which leads to a length-dependent thermal conductivity. In other words, heat conduction in low-dimensional nanostructures does not obey Fourier's law. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA.
Mon, 11 Feb 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/989662013-02-11T00:00:00Z
- Heat current limiter and constant heat current sourcehttps://scholarbank.nus.edu.sg/handle/10635/96770Title: Heat current limiter and constant heat current source
Authors: Wu, J.; Wang, L.; Li, B.
Abstract: Current limiters and constant current sources, which play important roles in electronic circuits, have been built up for many decades. Their thermal counterparts, heat current limiters and constant heat current sources, are still not available yet. By combining two typical nonlinear lattices, the Frenkel-Kontorova (FK) lattice and a coupled rotator lattice, together, we present by numerical simulation a model that displays complete negative differential thermal resistance (NDTR). Namely, in a wide regime, the heat current that flows through this model is always a decreasing function of the temperature drop applied to it, no matter whether the change in the temperature drop is due to a change in the high or the low temperature. We show that, upon being properly set up, a complete NDTR can work as either a heat current limiter or a constant heat current source. © 2012 American Physical Society.
Mon, 11 Jun 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/967702012-06-11T00:00:00Z
- Heat conduction in one-dimensional nonintegrable systemshttps://scholarbank.nus.edu.sg/handle/10635/96768Title: Heat conduction in one-dimensional nonintegrable systems
Authors: Hu, B.; Li, B.; Zhao, H.
Abstract: Two classes of one-dimensional nonintegrahle systems represented by the Fermi-Pasta-Ulam (FPU) model and the discrete φ4 model are studied to seek a generic mechanism of energy transport on a microscopic level sustaining macroscopic behaviors. The results enable us to understand why the class represented by the φ4 model has a normal thermal conductivity and the class represented by the FPU model does not even though the temperature gradient can be established.
Sat, 01 Apr 2000 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/967682000-04-01T00:00:00Z
- Stability of quantum motion: A semiclassical approachhttps://scholarbank.nus.edu.sg/handle/10635/98895Title: Stability of quantum motion: A semiclassical approach
Authors: Wang, W.-G.; Li, B.
Abstract: A semiclassical theory is used for the study of fidelity. For systems with weak chaos in the classical limit, we show that the fidelity has a non-Fermi-Golden-Rule decay, which can be explained by the closeness of the distribution of action difference in the semiclassical theory to the Levy distribution. For systems with strong chaos in the classical limit, we present a semiclassical expression for fidelity decay in the Lyapunov regime, which is more general than the previously predicted Lyapunov decay and λ1 decay of fidelity. For systems with regular motion in the classical limit, we derive the fidelity decay for initial narrow Gaussian wavepackets, which displays a quite complex behaviour, from Gaussian to power law decay t-α with 1 ≤ α ≤ 2. © World Scientific Publishing Company.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/988952007-09-30T00:00:00Z
- Pumping current in a quantum dot by an oscillating magnetic fieldhttps://scholarbank.nus.edu.sg/handle/10635/98859Title: Pumping current in a quantum dot by an oscillating magnetic field
Authors: Zhao, Y.Z.; Li, H.; Li, B.
Abstract: We investigate spin and charge current through a quantum dot pumped by a time-varying magnetic field. Using the density matrix method, quantum rate equations for the electronic occupation numbers in the quantum dot are obtained and solved in the stationary state limit for a wide set of parameters. Both charge and spin currents are expressed explicitly in terms of several relevant parameters and analyzed in detail. The results suggest a way of optimizing experimental parameters to obtain an maximal spin current without the charge current flow. © World Scientific Publishing Company.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/988592007-09-30T00:00:00Z
- Electronic transport in hybrid mesoscopic structures: A nonequilibrium Green function approachhttps://scholarbank.nus.edu.sg/handle/10635/96437Title: Electronic transport in hybrid mesoscopic structures: A nonequilibrium Green function approach
Authors: Zeng, Z.Y.; Li, B.; Claro, F.
Abstract: We present a unified transport theory of hybrid structures, in which a confined normal state (N) sample is sandwiched between two leads each of which can be either a ferromagnet (F) or a superconductor (S) via tunnel barriers. By introducing a four-dimensional Nambu-spinor space, a general current formula is derived within the Keldysh nonequilibrium Green function formalism, which can be applied to various kinds of hybrid mesoscopic systems with strong correlations even in the nonequilibrium situation. Such a formula is gauge invariant. We also demonstrate analytically for some quantities, such as the difference between chemical potentials, superconductor order parameter phases, and ferromagnetic magnetization orientations, that only their relative value appears explicitly in the current expression. When applied to specific structures, the formula becomes of the Meir-Wingreen-type favoring strong correlation effects, and reduces to the Landauer-Büttiker-type in noninteracting systems such as the double-barrier resonant structures, which we study in detail beyond the wide-band approximation. We find that the spin-dependent density of states of the ferromagnetic lead(s) is reflected in the resonant peak and resonant shoulder structure of the 1-V characteristics of F/I/N/I/F structures with large level spacing. The tunnel magnetoresistance that exhibits complex behaviors as a function of the bias voltage, can be either positive or negative, suppressed or enhanced within the resonant peak region(s), depending on the couplings to the leads. The Andreev current spectrum of F/I/N/I/S structures consists of a series of resonant peaks as a function of the gate voltage, of which the number and amplitude are strongly dependent on the bias voltage, degree of spin polarization of the ferromagnetic lead, energy gap of the superconducting lead, and the level configuration of the central region. In S/I/N/I/S resonant structures with asymmetric superconducting energy gaps, the Josephson current through a single resonant level is slightly enhanced in contrast to the significant enhancement of the Josephson current in S/N/S junctions. The current-phase relation is relevant to the level position and the couplings to the superconducting leads.
Mon, 01 Sep 2003 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/964372003-09-01T00:00:00Z
- Electronic properties of the 1D Frenkel-Kontorova modelhttps://scholarbank.nus.edu.sg/handle/10635/96427Title: Electronic properties of the 1D Frenkel-Kontorova model
Authors: Tong, P.; Li, B.; Hu, B.
Abstract: Electronic properties of one-dimensional Frenkel-Kontorova (FK) model was were studied. The energy spectra and quantum diffusion of an electron was studied numerically in FK chains. Electron eigenenergies were obtained numerically by the transfer matrix method. Different behaviors were observed for the spectral and dynamical properties of an electron display in the invariance circle regime and in the Cantorus regime. The relationship between transport and spectral properties was also discussed.
Mon, 28 Jan 2002 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/964272002-01-28T00:00:00Z
- Finite thermal conductivity in 1D models having zero Lyapunov exponentshttps://scholarbank.nus.edu.sg/handle/10635/96637Title: Finite thermal conductivity in 1D models having zero Lyapunov exponents
Authors: Li, B.; Wang, L.; Hu, B.
Abstract: Heat conduction was studied in different 1D Ehrenfest channels. It was found that the temperature gradient can be formed in all cases. However, a finite thermal conductivity was reached only when the disorder exists. It was concluded that the finite thermal conductivity might have nothing to do with the underlying dynamics.
Mon, 03 Jun 2002 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/966372002-06-03T00:00:00Z
- International Journal of Modern Physics: Prefacehttps://scholarbank.nus.edu.sg/handle/10635/98763Title: International Journal of Modern Physics: Preface
Authors: Li, B.; Tang, L.-H.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/987632007-09-30T00:00:00Z
- Interface thermal resistance between Frenkel-Kontorova and Fermi-Pasta-Ulam latticeshttps://scholarbank.nus.edu.sg/handle/10635/98762Title: Interface thermal resistance between Frenkel-Kontorova and Fermi-Pasta-Ulam lattices
Authors: Lan, J.; Wang, L.; Li, B.
Abstract: By connecting two dissimilar anharmonic lattices exemplified by Fermi-Pasta-Ulam (FPU) model and Frenkel-kontorova (FK) model, we successfully build up one dimensional thermal diode. We find the rectifying effect is closely related to asymmetric interface thermal resistance ( Kapitza resistance). And the asymmetric thermal resistance depends on how the temperature gradient is applied. Moreover, a quatitative relationship between the thermal rectification and the phonon spectra is propsoed. © World Scientific Publishing Company.
Sun, 30 Sep 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/987622007-09-30T00:00:00Z
- Intriguing Heat Conduction of a Chain with Transverse Motionshttps://scholarbank.nus.edu.sg/handle/10635/96973Title: Intriguing Heat Conduction of a Chain with Transverse Motions
Authors: Wang, J.-S.; Li, B.
Abstract: Heat conduction in a one-dimensional chain of particles was investigated. The particles were connected by two-dimensional harmonic springs. A simple mode-coupling analysis was performed. Three types of thermal conducting behaviors were found using equilibrium and nonequlibrium molecular dynamics. It was suggested that power-law divergence should be a generic feature for such models.
Fri, 20 Feb 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/969732004-02-20T00:00:00Z
- Phononics gets hothttps://scholarbank.nus.edu.sg/handle/10635/97530Title: Phononics gets hot
Authors: Wang, L.; Li, B.
Sat, 01 Mar 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/975302008-03-01T00:00:00Z
- Pathway sensitivity analysis for detecting pro-proliferation activities of oncogenes and tumor suppressors of epidermal growth factor receptor- extracellular signal-regulated protein kinase pathway at altered protein levelshttps://scholarbank.nus.edu.sg/handle/10635/53083Title: Pathway sensitivity analysis for detecting pro-proliferation activities of oncogenes and tumor suppressors of epidermal growth factor receptor- extracellular signal-regulated protein kinase pathway at altered protein levels
Authors: Li, H.; Choong, Y.U.; Xiao, H.M.; Xiang, H.L.; Bao, W.L.; Boon, C.L.; Yu, Z.C.
Abstract: BACKGROUND: Mathematic models and sensitivity analyses of biologic pathways have been used for exploring the dynamics and for detecting the key components of signaling pathways. METHODS: The authors previously developed a mathematic model of the epidermal growth factor receptor-extracellular signal-regulated protein kinase (EGFR-ERK) pathway using ordinary differential equations from existing EGFR-ERK pathway models. By using prolonged ERK activation as an indicator that may lead to cell proliferation under certain circumstances, in the current study, a pathway sensitivity analysis was performed to test its capability of detecting pro-proliferative activities through altered protein levels to examine the effects on ERK activation. RESULTS: The analysis revealed that 12 of 20 oncoproteins and 4 of 5 tumor suppressors were detected, consistent with reported experimental works. Because pathway dynamics depend on many factors, some of which were not included in the current models, failure to detect all known oncogenes and tumor suppressors can be because of the failure to include relevant crosstalk to other pathway components. CONCLUSIONS: Overall, the current results indicated that pathway sensitivity analysis is a useful approach for detecting and distinguishing pro-proliferation activities of oncoproteins and suppressed proliferative activities of tumor suppressors at altered protein levels at least in the EGFR-ERK model. © 2009 American Cancer Society.
Tue, 15 Sep 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/530832009-09-15T00:00:00Z
- Linking agent-based models and stochastic models of financial marketshttps://scholarbank.nus.edu.sg/handle/10635/53012Title: Linking agent-based models and stochastic models of financial markets
Authors: Feng, L.; Li, B.; Podobnik, B.; Preis, T.; Stanley, H.E.
Abstract: It is well-known that financial asset returns exhibit fat-tailed distributions and long-term memory. These empirical features are the main objectives of modeling efforts using (i) stochastic processes to quantitatively reproduce these features and (ii) agent-based simulations to understand the underlying microscopic interactions. After reviewing selected empirical and theoretical evidence documenting the behavior of traders, we construct an agent-based model to quantitatively demonstrate that "fat" tails in return distributions arise when traders share similar technical trading strategies and decisions. Extending our behavioral model to a stochastic model, we derive and explain a set of quantitative scaling relations of long-term memory from the empirical behavior of individual market participants. Our analysis provides a behavioral interpretation of the long-term memory of absolute and squared price returns: They are directly linked to the way investors evaluate their investments by applying technical strategies at different investment horizons, and this quantitative relationship is in agreement with empirical findings. Our approach provides a possible behavioral explanation for stochastic models for financial systems in general and provides a method to parameterize such models from market data rather than from statistical fitting.
Tue, 29 May 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/530122012-05-29T00:00:00Z
- Spectral analysis of gene co-expression network of Zebrafishhttps://scholarbank.nus.edu.sg/handle/10635/53185Title: Spectral analysis of gene co-expression network of Zebrafish
Authors: Jalan, S.; Ung, C.Y.; Bhojwani, J.; Li, B.; Zhang, L.; Lan, S.H.; Gong, Z.
Abstract: We analyze the gene expression data of Zebrafish under the combined framework of complex networks and random matrix theory. The nearest-neighbor spacing distribution of the corresponding matrix spectra follows random matrix predictions of Gaussian orthogonal statistics. Based on the eigenvector analysis we can divide the spectra into two parts, the first part for which the eigenvector localization properties match with the random matrix theory predictions, and the second part for which they show deviation from the theory and hence are useful to understand the system-dependent properties. Spectra with the localized eigenvectors can be characterized into three groups based on the eigenvalues. We explore the position of localized nodes from these different categories. Using an overlap measure, we find that the top contributing nodes in the different groups carry distinguished structural features. Furthermore, the top contributing nodes of the different localized eigenvectors corresponding to the lower eigenvalue regime form different densely connected structure well separated from each other. Preliminary biological interpretation of the genes, associated with the top contributing nodes in the localized eigenvectors, suggests that the genes corresponding to same vector share common features. © 2012 Copyright EPLA.
Wed, 01 Aug 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/531852012-08-01T00:00:00Z
- Phononics: A new science and technology of controlling heat flow and processing information by phononshttps://scholarbank.nus.edu.sg/handle/10635/53310Title: Phononics: A new science and technology of controlling heat flow and processing information by phonons
Authors: Wang, L.; Zhang, G.; Wu, G.; Yang, N.; Li, B.
Abstract: Heat due to lattice vibration (phonons) is traditionally regarded as harmful for information processing. In this paper, we will demonstrate via numerical simulation, theoretical analysis and experiments that, phonons, can be manipulated like electrons. They can be used to carry and process information. Basic phononic devices such as thermal diode, thermal transistor, thermal logic gate and thermal memory will be discussed via nonlinear lattice model. Moreover, we will also discuss how to manipulate and tune thermal conductivity of nanostructure so that to control heat flow. Both theoretical and experimental works will be shown. © 2010 by ASME.
Fri, 01 Jan 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/533102010-01-01T00:00:00Z
- Comment on "Anomalous Heat Conduction and Anomalous Diffusion in One-Dimensional Systems" [1] (multiple letters)https://scholarbank.nus.edu.sg/handle/10635/111658Title: Comment on "Anomalous Heat Conduction and Anomalous Diffusion in One-Dimensional Systems" [1] (multiple letters)
Authors: Metzler, R.; Sokolov, I.M.; Li, B.; Wang, J.
Fri, 27 Feb 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1116582004-02-27T00:00:00Z
- Anomalous heat conduction, diffusion and heat rectification in nanoscale structureshttps://scholarbank.nus.edu.sg/handle/10635/53274Title: Anomalous heat conduction, diffusion and heat rectification in nanoscale structures
Authors: Zhang, G.; Yang, N.; Wu, G.; Li, B.
Abstract: In this paper, we report the recent developments in the study of heat transport in nano materials. First of all, we show that phonon transports in nanotube super-diffusively which leads to a length dependence thermal conductivity, thus breaks down the Fourier law. Then we discuss how the introduction of isotope doping can reduce the thermal conductivity efficiently. The theoretical results are in good agreement with experimental ones. Finally, we will demonstrate that nanoscale structures are promising candidates for heat rectification. Copyright © 2009 by ASME.
Fri, 01 Jan 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/532742010-01-01T00:00:00Z
- Homogeneous thermal cloak with constant conductivity and tunable heat localizationhttps://scholarbank.nus.edu.sg/handle/10635/50940Title: Homogeneous thermal cloak with constant conductivity and tunable heat localization
Authors: Han, T.; Yuan, T.; Li, B.; Qiu, C.-W.
Abstract: Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons.
Tue, 01 Jan 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/509402013-01-01T00:00:00Z
- Disorder enhances thermoelectric figure of merit in armchair graphane nanoribbonshttps://scholarbank.nus.edu.sg/handle/10635/50897Title: Disorder enhances thermoelectric figure of merit in armchair graphane nanoribbons
Authors: Ni, X.; Liang, G.; Wang, J.-S.; Li, B.
Abstract: We study the thermoelectric property of graphane strips by using density functional theory calculations combined with the nonequilibrium Green's function method. It is found that figure of merit (ZT) can be remarkably enhanced five times by randomly introducing hydrogen vacancies to the graphene nanoribon derivatives-armchair graphane nanoribbons. For 5 nm wide ribbons under certain conditions, ZT can be as high as 5.8 and depends on temperature linearly. The high ZT, low cost, and rapid advances in the synthesis of nanoscale graphene derivatives make carbon-based materials a viable choice for thermoelectric applications. © 2009 American Institute of Physics.
Thu, 01 Jan 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/508972009-01-01T00:00:00Z
- Reverse engineering of complex dynamical networks in the presence of time-delayed interactions based on noisy time serieshttps://scholarbank.nus.edu.sg/handle/10635/97821Title: Reverse engineering of complex dynamical networks in the presence of time-delayed interactions based on noisy time series
Authors: Wang, W.-X.; Ren, J.; Lai, Y.-C.; Li, B.
Abstract: Reverse engineering of complex dynamical networks is important for a variety of fields where uncovering the full topology of unknown networks and estimating parameters characterizing the network structure and dynamical processes are of interest. We consider complex oscillator networks with time-delayed interactions in a noisy environment, and develop an effective method to infer the full topology of the network and evaluate the amount of time delay based solely on noise-contaminated time series. In particular, we develop an analytic theory establishing that the dynamical correlation matrix, which can be constructed purely from time series, can be manipulated to yield both the network topology and the amount of time delay simultaneously. Extensive numerical support is provided to validate the method. While our method provides a viable solution to the network inverse problem, significant difficulties, limitations, and challenges still remain, and these are discussed thoroughly. © 2012 American Institute of Physics.
Thu, 05 Jul 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/978212012-07-05T00:00:00Z
- Nonequilibrium Green's function method for phonon-phonon interactions and ballistic-diffusive thermal transporthttps://scholarbank.nus.edu.sg/handle/10635/97336Title: Nonequilibrium Green's function method for phonon-phonon interactions and ballistic-diffusive thermal transport
Authors: Xu, Y.; Wang, J.-S.; Duan, W.; Gu, B.-L.; Li, B.
Abstract: Phonon-phonon interactions are systematically studied by nonequilibrium Green's function (NEGF) formalism in momentum space at finite temperatures. Within the quasiparticle approximation, phonon frequency shift and lifetime are obtained from the retarded self-energy. The lowest-order NEGF provides the same phonon lifetime as Fermi's golden rule. Thermal conductance is predicted by the Landauer formula with a phenomenological transmission function. The main advantage of our method is that it covers both ballistic and diffusive limits, and thermal conductance of different system sizes can be easily obtained once the mode-dependent phonon mean-free path is calculated by NEGF. As an illustration, the method is applied to two one-dimensional atom chain models [the Fermi-Pasta-Ulam (FPU)-β model and the φ4 model] with an additional harmonic on-site potential. The obtained thermal conductance is compared with that from a quasiclassical molecular-dynamics method. The harmonic on-site potential is shown to remove the divergence of thermal conductivity in the FPU-β model. © 2008 The American Physical Society.
Mon, 01 Dec 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/973362008-12-01T00:00:00Z
- Anomalous heat conduction and anomalous diffusion in nonlinear lattices, single walled nanotubes, and billiard gas channelshttps://scholarbank.nus.edu.sg/handle/10635/116229Title: Anomalous heat conduction and anomalous diffusion in nonlinear lattices, single walled nanotubes, and billiard gas channels
Authors: Li, B.; Wang, J.; Wang, L.; Zhang, G.
Abstract: We study anomalous heat conduction and anomalous diffusion in low-dimensional systems ranging from nonlinear lattices, single walled carbon nanotubes, to billiard gas channels. We find that in all discussed systems, the anomalous heat conductivity can be connected with the anomalous diffusion, namely, if energy diffusion is o 2(t)=2Dt α (0 < α ≤ 2), then the thermal conductivity can be expressed in terms of the system size L as K=cL β with β=2-2/α. This result predicts that a normal diffusion (a=l) implies a normal heat conduction obeying the Fourier law (β=0), a superdiffusion (α > 1) implies an anomalous heat conduction with a divergent thermal conductivity (β>0), and more interestingly, a subdiffusion (α < 1) implies an anomalous heat conduction with a convergent thermal conductivity (β < 0), consequently, the system is a thermal insulator in the thermodynamic limit. Existing numerical data support our theoretical prediction. © 2005 American Institute of Physics.
Sat, 01 Jan 2005 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1162292005-01-01T00:00:00Z
- Symmetry breaking and self-trapping of a dipolar Bose-Einstein condensate in a double-well potentialhttps://scholarbank.nus.edu.sg/handle/10635/53203Title: Symmetry breaking and self-trapping of a dipolar Bose-Einstein condensate in a double-well potential
Authors: Xiong, B.; Gong, J.; Pu, H.; Bao, W.; Li, B.
Abstract: The quantum self-trapping phenomenon of a Bose-Einstein condensate (BEC) represents a remarkable nonlinear effect of wide interest. By considering a purely dipolar BEC in a double-well potential, we study how the dipole orientation affects the ground-state structure and the transition between self-trapping and Josephson oscillations in dynamics. Three-dimensional numerical results and an effective two-mode model demonstrate that the onset of self-trapping of a dipolar BEC can be radically modified by the dipole orientation. We also analyze the failure of the two-mode model in predicting the rate of Josephson oscillations. We hope that our results can motivate experimental work as well as future studies of self-trapping of ultracold dipolar gases in optical lattices. © 2009 The American Physical Society.
Mon, 05 Jan 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/532032009-01-05T00:00:00Z
- Spectral properties of directed random networks with modular structurehttps://scholarbank.nus.edu.sg/handle/10635/97981Title: Spectral properties of directed random networks with modular structure
Authors: Jalan, S.; Zhu, G.; Li, B.
Abstract: We study spectra of directed networks with inhibitory and excitatory couplings. We investigate in particular eigenvector localization properties of various model networks for different values of correlation among their entries. Spectra of random networks with completely uncorrelated entries show a circular distribution with delocalized eigenvectors, whereas networks with correlated entries have localized eigenvectors. In order to understand the origin of localization we track the spectra as a function of connection probability and directionality. As connections are made directed, eigenstates start occurring in complex-conjugate pairs and the eigenvalue distribution combined with the localization measure shows a rich pattern. Moreover, for a very well distinguished community structure, the whole spectrum is localized except few eigenstates at the boundary of the circular distribution. As the network deviates from the community structure there is a sudden change in the localization property for a very small value of deformation from the perfect community structure. We search for this effect for the whole range of correlation strengths and for different community configurations. Furthermore, we investigate spectral properties of a metabolic network of zebrafish and compare them with those of the model networks. © 2011 American Physical Society.
Tue, 18 Oct 2011 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/979812011-10-18T00:00:00Z
- Heat flux distribution and rectification of complex networkshttps://scholarbank.nus.edu.sg/handle/10635/96771Title: Heat flux distribution and rectification of complex networks
Authors: Liu, Z.; Wu, X.; Yang, H.; Gupte, N.; Li, B.
Abstract: It was recently found that the heterogeneity of complex networks can enhance transport properties such as epidemic spreading, electric energy transfer, etc. A trivial deduction would be that the presence of hubs in complex networks can also accelerate the heat transfer although no concrete research has been done so far. In the present study, we have studied this problem and have found a surprising answer: the heterogeneity does not favor but prevents the heat transfer. We present a model to study heat conduction in complex networks and find that the network topology greatly affects the heat flux. The heat conduction decreases with the increase of heterogeneity of the network caused by both degree distribution and the clustering coefficient. Its underlying mechanism can be understood by using random matrix theory. Moreover, we also study the rectification effect and find that it is related to the degree difference of the network, and the distance between the source and the sink. These findings may have potential applications in real networks, such as nanotube/nanowire networks and biological networks. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Thu, 11 Feb 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/967712010-02-11T00:00:00Z
- Effects of lithium insertion on thermal conductivity of silicon nanowireshttps://scholarbank.nus.edu.sg/handle/10635/127196Title: Effects of lithium insertion on thermal conductivity of silicon nanowires
Authors: Xu, Wen; Zhang, Gang; Li, Baowen
Thu, 01 Jan 2015 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/1271962015-01-01T00:00:00Z
- Thermal conductance of graphene and dimeritehttps://scholarbank.nus.edu.sg/handle/10635/98346Title: Thermal conductance of graphene and dimerite
Authors: Jiang, J.-W.; Wang, J.-S.; Li, B.
Abstract: We investigate the phonon thermal conductance of graphene regarding the graphene sheet as the large-width limit of graphene strips in the ballistic limit. We find that the thermal conductance depends weakly on the direction angle θ of the thermal flux periodically with period π/3. It is further shown that the nature of this directional dependence is the directional dependence of group velocities of the phonon modes in the graphene, originating from the D6h symmetry in the honeycomb structure. By breaking the D6h symmetry in graphene, we see more obvious anisotropic effect in the thermal conductance as demonstrated by dimerite. © 2009 The American Physical Society.
Fri, 01 May 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/983462009-05-01T00:00:00Z
- Remarkable reduction of thermal conductivity in silicon nanotubeshttps://scholarbank.nus.edu.sg/handle/10635/97800Title: Remarkable reduction of thermal conductivity in silicon nanotubes
Authors: Chen, J.; Zhang, G.; Li, B.
Abstract: We propose to reduce the thermal conductivity of silicon nanowires (SiNWs) by introducing a small hole at the center, i.e., construct a silicon nanotube (SiNT) structure. Our numerical results demonstrate that a very small hole (only 1% reduction in cross section area) can induce a 35% reduction in room temperature thermal conductivity. Moreover, with the same cross section area, thermal conductivity of SiNT is only about 33% of that of SiNW at room temperature. The spatial distribution of vibrational energy reveals that localization modes are concentrated on the inner and outer surfaces of SiNTs. The enhanced surface-to-volume ratio in SiNTs reduces the percentage of delocalized modes, which is believed to be responsible for the reduction of thermal conductivity. Our study suggests SiNT is a promising thermoelectric material with low thermal conductivity. © 2010 American Chemical Society.
Wed, 13 Oct 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/978002010-10-13T00:00:00Z
- Stability of quantum motion in regular systems: A uniform semiclassical approachhttps://scholarbank.nus.edu.sg/handle/10635/98012Title: Stability of quantum motion in regular systems: A uniform semiclassical approach
Authors: Wang, W.-G.; Casati, G.; Li, B.
Abstract: We study the stability of quantum motion of classically regular systems in the presence of small perturbations. On the basis of a uniform semiclassical theory we derive the fidelity decay which displays a quite complex behavior, from Gaussian to power law decay t-α, with 1≤α≤2. Semiclassical estimates are given for the time scales separating the different decaying regions, and numerical results are presented which confirm our theoretical predictions. © 2007 The American Physical Society.
Mon, 01 Jan 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/980122007-01-01T00:00:00Z
- Thermal rectification in asymmetric graphene ribbonshttps://scholarbank.nus.edu.sg/handle/10635/98364Title: Thermal rectification in asymmetric graphene ribbons
Authors: Yang, N.; Zhang, G.; Li, B.
Abstract: In this paper, heat flux in graphene nanoribbons has been studied by using molecular dynamics simulations. It is found that the heat flux runs preferentially along the direction of decreasing width, which demonstrates significant thermal rectification effect in the asymmetric graphene ribbons. The dependence of rectification ratio on the vertex angle and the length are also discussed. Compared to the carbon nanotube based one-dimensional thermal rectifier, graphene nanoribbons have much higher rectification ratio even in large scale. Our results demonstrate that asymmetric graphene ribbon might be a promising structure for practical thermal (phononics) device. © 2009 American Institute of Physics.
Thu, 01 Jan 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/983642009-01-01T00:00:00Z
- Violation of Fourier's law and anomalous heat diffusion in silicon nanowireshttps://scholarbank.nus.edu.sg/handle/10635/98561Title: Violation of Fourier's law and anomalous heat diffusion in silicon nanowires
Authors: Yang, N.; Zhang, G.; Li, B.
Abstract: We study heat conduction and diffusion in silicon nanowires (SiNWs) systematically by using non-equilibrium molecular dynamics. It is found that the thermal conductivity (κ) of SiNWs diverges with the length as, κ ∝ Lβ, even when the length is up to 1.1 μm which is much longer than the phonon mean free path. The dependences of β on temperature and length are also discussed. Moreover, an anomalous heat diffusion is observed which is believed to be responsible for the length dependent thermal conductivity. Our results provide strong evidence that Fourier's law of heat conduction is not valid in low-dimensional nanostructures. © 2010 Elsevier Ltd. All rights reserved.
Thu, 01 Apr 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/985612010-04-01T00:00:00Z
- Thermal conductivity and thermal rectification in unzipped carbon nanotubeshttps://scholarbank.nus.edu.sg/handle/10635/98347Title: Thermal conductivity and thermal rectification in unzipped carbon nanotubes
Authors: Ni, X.; Zhang, G.; Li, B.
Abstract: We study the thermal transport in completely unzipped carbon nanotubes, which are called graphene nanoribbons, partially unzipped carbon nanotubes, which can be seen as carbon-nanotube-graphene-nanoribbon junctions, and carbon nanotubes by using molecular dynamics simulations. It is found that the thermal conductivity of a graphene nanoribbon is much less than that of its perfect carbon nanotube counterparts because of the localized phonon modes at the boundary. A partially unzipped carbon nanotube has the lowest thermal conductivity due to additional localized modes at the junction region. More strikingly, a significant thermal rectification effect is observed in both partially unzipped armchair and zigzag carbon nanotubes. Our results suggest that carbon-nanotube-graphene-nanoribbon junctions can be used in thermal energy control. © 2011 IOP Publishing Ltd.
Wed, 01 Jun 2011 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/983472011-06-01T00:00:00Z
- Energy carriers in the fermi-pasta-ulam β lattice: Solitons or phonons?https://scholarbank.nus.edu.sg/handle/10635/96455Title: Energy carriers in the fermi-pasta-ulam β lattice: Solitons or phonons?
Authors: Li, N.; Li, B.; Flach, S.
Abstract: We investigate anomalous energy transport processes in the Fermi-Pasta-Ulam β lattice, in particular, the maximum sound velocity of the relevant weakly damped energy carriers. That velocity is numerically resolved by measuring the propagating fronts of the correlation functions of energy-momentum fluctuations at different times. We use fixed boundary conditions and stochastic heat baths. The numerical results are compared with the theoretical predictions of the sound velocities for solitons and effective (renormalized) phonons, respectively. Excellent agreement has been found for the prediction of effective long wavelength phonons, giving strong evidence that the energy carriers should be effective phonons rather than solitons. © 2010 The American Physical Society.
Tue, 27 Jul 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/964552010-07-27T00:00:00Z
- Fidelity of a Bose-Einstein condensateshttps://scholarbank.nus.edu.sg/handle/10635/96625Title: Fidelity of a Bose-Einstein condensates
Authors: Liu, J.; Wang, W.; Zhang, C.; Niu, Q.; Li, B.
Abstract: We investigate fidelity for the quantum evolution of a Bose-Einstein condensate and reveal its general property with a simple model. We find the fidelity decay with time in various ways depending on the form of initial states as well as on mean-field dynamics. When the initial state is a coherent state, the fidelity decays with time in the ways of exponential, Gaussian, and power-law, having a close relation to the classical mean-field dynamics. With the initial state prepared as a maximally entangled state, we find the behavior of fidelity has no classical correspondence and observe a novel behavior of the fidelity: periodic revival, where the period is inversely proportional to the number of bosons and the perturbation strength. An experimental observation of the fidelity decay is suggested. © 2005 Elsevier B.V. All rights reserved.
Mon, 24 Apr 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/966252006-04-24T00:00:00Z
- Thermal memory: A storage of phononic informationhttps://scholarbank.nus.edu.sg/handle/10635/98360Title: Thermal memory: A storage of phononic information
Authors: Wang, L.; Li, B.
Abstract: Memory is an indispensible element for a computer in addition to logic gates. In this Letter we report a model of thermal memory. We demonstrate via numerical simulation that thermal (phononic) information stored in the memory can be retained for a long time without being lost and more importantly can be read out without being destroyed. The possibility of experimental realization is also discussed. © 2008 The American Physical Society.
Mon, 22 Dec 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/983602008-12-22T00:00:00Z
- Redirection of sound waves using acoustic metasurfacehttps://scholarbank.nus.edu.sg/handle/10635/57218Title: Redirection of sound waves using acoustic metasurface
Authors: Zhao, J.; Li, B.; Chen, Z.N.; Qiu, C.-W.
Abstract: When acoustic waves are impinged on an impedance surface in fluids, it is challenging to alter the vibration of fluid particles since the vibrational direction of reflected waves shares the same plane of the incidence and the normal direction of the surface. We demonstrate a flat acoustic metasurface that generates an extraordinary reflection, and such metasurface can steer the vibration of the reflection out of the incident plane. Remarkably, the arbitrary direction of the extraordinary reflection can be predicted by a Green's function formulation, and our approach can completely convert the incident waves into the extraordinary reflection without parasitic ordinary reflection. © 2013 AIP Publishing LLC.
Mon, 07 Oct 2013 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/572182013-10-07T00:00:00Z
- High thermoelectric figure of merit in silicon-germanium superlattice structured nanowireshttps://scholarbank.nus.edu.sg/handle/10635/96798Title: High thermoelectric figure of merit in silicon-germanium superlattice structured nanowires
Authors: Shi, L.; Jiang, J.; Zhang, G.; Li, B.
Abstract: By using a combination of the first-principles density functional theory and nonequilibrium Greens function for electron and phonon transport, we investigate the thermoelectric properties of silicon-germanium superlattice nanowires (NWs). Our results show that introducing superlattice structures always increases thermoelectric figure of merit, ZT, which depends on the periodic length of the superlattice NWs. For n-type superlattice NWs, the achievable maximum ZT is 4.7, which is 5-fold increase as compared to the equivalent pristine silicon NWs. For p-type wires, the achieved maximum ZT is 2.74, which is 4.6-fold increase as compared to the pristine silicon NWs. © 2012 American Institute of Physics.
Mon, 03 Dec 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/967982012-12-03T00:00:00Z
- Diameter-dependent thermal transport in individual ZnO nanowires and its correlation with surface coating and defectshttps://scholarbank.nus.edu.sg/handle/10635/82152Title: Diameter-dependent thermal transport in individual ZnO nanowires and its correlation with surface coating and defects
Authors: Bui, C.T.; Xie, R.; Zheng, M.; Zhang, Q.; Sow, C.H.; Li, B.; Thong, J.T.L.
Abstract: A systematic study of the thermal transport properties of individual single-crystal zinc oxide (ZnO) nanowires (NWs) with diameters in the range of ∼50-210 nm is presented. The thermal conductivity of the NWs is found to be dramatically reduced by at least an order of magnitude compared to bulk values, due to enhanced phonon-boundary scattering with a reduction in sample size. While the conventional phonon transport model can qualitatively explain the temperature dependence, it fails to account for the diameter dependence. An empirical relationship for assessing diameter-dependent thermal properties is observed, which shows an approximately linear dependence of the thermal conductivity on the cross-sectional area of the NWs in the measured diameter range. Furthermore, it is found that an amorphous-carbon layer coating on the NWs does not perturb the thermal properties of the NW cores, whereas 30 keV Ga + ion irradiation at low dose (∼4 ×10 14 cm -2) leads to a remarkable reduction of the thermal conductivity of the ZnO NWs. Thermal transport properties of individual zinc oxide nanowires are characterized using a suspended micro-electro-thermal device. It is found that the thermal conductivities of the nanowires are dramatically reduced by at least one order of magnitude compared to bulk values. An empirical relationship for assessing diameter-dependent thermal properties is observed, which shows an approximately linear dependence of the thermal conductivity on the cross-section area of the nanowires in the measured diameter range. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mon, 12 Mar 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/821522012-03-12T00:00:00Z
- Stability of quantum motion: Beyond Fermi-golden-rule and Lyapunov decayhttps://scholarbank.nus.edu.sg/handle/10635/98013Title: Stability of quantum motion: Beyond Fermi-golden-rule and Lyapunov decay
Authors: Wang, W.-G.; Casati, G.; Li, B.
Abstract: The stability of quantum motion for a classically chaotic system is discussed. The existence of different regimes of fidelity decay is shown. The deviations from Fermi-golden-rule and Lyapunov regimes are observed when the underlying classical dynamics is weakly chaotic. It is found that fidelity is an important quantity which characterizes the stability of quantum and classical systems.
Sun, 01 Feb 2004 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/980132004-02-01T00:00:00Z
- Young's modulus of graphene: A molecular dynamics studyhttps://scholarbank.nus.edu.sg/handle/10635/98614Title: Young's modulus of graphene: A molecular dynamics study
Authors: Jiang, J.-W.; Wang, J.-S.; Li, B.
Abstract: The Young's modulus of graphene is investigated through the intrinsic thermal vibration in graphene which is "observed" by molecular dynamics and the results agree very well with the recent experiment. This method is further applied to show that the Young's modulus of graphene (1) increases with increasing size and saturates after a threshold value of the size; (2) increases from 0.95 to 1.1 TPa as temperature increases in the region [100, 500] K; (3) is insensitive to the isotopic disorder in the low disorder region (
Wed, 23 Sep 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/986142009-09-23T00:00:00Z
- Large thermoelectric figure of merit in Si1-x Gex nanowireshttps://scholarbank.nus.edu.sg/handle/10635/97043Title: Large thermoelectric figure of merit in Si1-x Gex nanowires
Authors: Shi, L.; Yao, D.; Zhang, G.; Li, B.
Abstract: By using first-principles electronic structure calculation and Boltzmann transport equation, we investigate composition effects on the thermoelectric properties of silicon-germanium (Si1-x Gex) nanowires (NWs). The power factor and figure of merit in n-type Si1-x Ge x wires are much larger than those in their p-type counterparts with the same Ge content and doping concentration. Moreover, the maximal obtainable figure of merit can be increased by a factor of 4.3 in n-type Si0.5 Ge0.5 NWs, compared with the corresponding values in pure silicon nanowires (SiNWs). Given the fact that the measured ZT of n-type SiNW is 0.6∼1.0, we expect Z T value of n-type Si1-x Gex NWs to be 2.5∼4.0. © 2010 American Institute of Physics.
Mon, 26 Apr 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/970432010-04-26T00:00:00Z