Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/121996
Title: THE ROLE OF ATOMIC INTERFACES ON ELECTRONIC, MAGNETIC AND SWITCHING PROPERTIES OF OXIDE HETEROSTRUCTURES
Authors: LI CHANGJIAN
Keywords: Oxides Heterostructures, Pulsed Laser Deposition, Magnetism, Polar Discontinuity, Two Dimensional Electron Gas, Ferroelectric Tunnel Junction
Issue Date: 31-Jul-2015
Citation: LI CHANGJIAN (2015-07-31). THE ROLE OF ATOMIC INTERFACES ON ELECTRONIC, MAGNETIC AND SWITCHING PROPERTIES OF OXIDE HETEROSTRUCTURES. ScholarBank@NUS Repository.
Abstract: Functional oxides with wide spectra of properties hold promising applications in future multifunctional devices. In this thesis, three materials systems, LaAlO<sub>3</sub>/SrTiO<sub>3</sub>, LaMnO<sub>3</sub>/SrTiO<sub>3</sub> and ferroelectric tunnel junction (FTJ) of Pt/(La<sub>0.67</sub>Sr<sub>0.33</sub>MnO<sub>3</sub>/La<sub>1-x</sub>Sr<sub>x</sub>MnO<sub>3</sub>/)BaTiO<sub>3</sub>//Nb:SrTiO<sub>3</sub> are studied for electronic, magnetic and switching properties, respectively. In LaAlO<sub>3</sub>/SrTiO<sub>3</sub>, we firstly clarified the origin of conductive interface between to band insulator, then revealed relative dominance of electron scattering mechanisms near the metal-insulator-transition regime and finally we determined a critical crystallinity (70 % at temperature 515 ?C) for two dimensional electron gas at the interface. In LaMnO<sub>3</sub>/SrTiO<sub>3</sub> interfaces, we conclusively demonstrated 6 unit cell (uc) of the critical thickness for the transition both in bulk and microscopic measurements with support of a theoretical model of the electronic reconstruction. In the ferroelectric tunnel junction study, we showed that additional interfaces increase tunnel electroresistance (TER) of an FTJ at the expense of the resistance area product (R<sub>ON</sub>A) originated from the band offset effects at the interfaces within an FTJ. We are the first to show TER of 400% at room temperature for FTJ of Pt/BaTiO<sub>3</sub>/Nb:SrTiO<sub>3</sub> with the BaTiO<sub>3</sub> only of 0.8 nm (2 uc). In summary, electrostatic boundary conditions and band offsets at oxide interfaces are extremely important parameters to be considered and utilized to build multifunctional devices.
URI: http://scholarbank.nus.edu.sg/handle/10635/121996
Appears in Collections:Ph.D Theses (Open)

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