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The Thoery of Transverse Ising Model of Ferroelectric Superlattice and the Simulant Calculation

Author: LuWei
Tutor: ZhuJianGuo
School: Sichuan University
Course: Condensed Matter Physics
Keywords: Transverse field Ising model Ferroelectric superlattices Attenuation factor BaTiO3/SrTiO3 BaTiO3/LaAlO3
CLC: O481
Type: Master's thesis
Year: 2005
Downloads: 259
Quote: 0
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Abstract


In this thesis, applied transverse field Ising model by considering superlattices four -body interaction , the introduction of the coupling between the interface was investigated ferroelectric superlattices spontaneous polarization , Curie temperature , dielectric constant and iron relationship between electric superlattice period . Obtained when the superlattice period is changed, its ferroelectric superlattices spontaneous polarization , Curie temperature , dielectric constant and so there will be significant size effect relationship . And each component ferroelectric superlattices formed of a material , its Curie temperature than the individual component materials is high. In this thesis, the main conclusions obtained are as follows: 1 , the application of transverse field Ising model by considering the nearest neighbor superlattice pseudo-spin interactions and four -body interaction , the Hamiltonian of the system is the introduction of the interface coupling between established ferroelectric superlattices TIM theoretical model . 2 , access to the macroscopic thermodynamic parameters and changes in the relationship between the microscopic parameters . According to the principle of minimum free energy , obtained two mutually coupled and the Euler-Lagrange equations. Fourth-order Runge-Kutta method or Euler predictor - corrector method for solving the simultaneous equations . Simulation obtained superlattice ferroelectric polarization , dielectric constant , dielectric loss, etc. and the temperature, the total thickness of the superlattice , the superlattice layer thickness of between 3 found as BTO / STO increase the total thickness of the superlattice , BTO 's polarization than the STO with a large scale that part of the BTO BTO / STO superlattice major contributor of polarization . 4, the study found that as BTO / STO superlattice thickness increases , BTO / STO dielectric superlattice peaks appeared two mutations . That this mainly reflects the different component superlattices with different critical size 's sake . 5 , in the ferroelectric superlattices TIM theoretical model based on ferroelectric superlattices considering the long-range interactions. Through the BTO / STO superlattice Curie temperature simulation found that when the decay exponent σ Take 3

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CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Solid State Theory
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