Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/139097
Title: THERMAL STRUCTURAL INSTABILITY AND MAGNETORESISTANCE IN EUTIO3
Authors: QIU HONGFEI
Keywords: colossal magnetoresistance,soft mode,spin Green's function,EuTiO3
Issue Date: 23-Aug-2017
Citation: QIU HONGFEI (2017-08-23). THERMAL STRUCTURAL INSTABILITY AND MAGNETORESISTANCE IN EUTIO3. ScholarBank@NUS Repository.
Abstract: Due to the potential of being multiferroics, the interest in $EuTiO_3$ (ETO) has aroused in recent years. Rich phenomena due to coupling between magnetism, electron, and phonon, make ETO so fascinating. Among all these properties, magnetoresistance and soft mode phonon frequency are studied in this thesis. Firstly, the influence of second-order Jahn-Teller effect on anharmonic phonon is investigated, and I find second-order coupling can enhance the softness of soft mode frequency. The anharmonic oscillation is also stabilized by such coupling under proper condition. Secondly, a combinational method of NEGF and Boltzmann equation is used to inspect several possible causes for large colossal magnetoresistance, and it confirms the important contribution of the molecular field. Thirdly, an algorithm to obtain spin Green's functions of the arbitrary nano-size spin system is proposed, which suggests a possible way to investigate the quantum transport of nano-size spintronic devices.
URI: http://scholarbank.nus.edu.sg/handle/10635/139097
Appears in Collections:Ph.D Theses (Open)

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