scholarly journals External tuning of topological phase transitions induced by interaction driven mass renormalization

2021 ◽  
Author(s):  
Thies Jansen ◽  
Alexander Brinkman
Keyword(s):  
Phase Transition ◽  
Mean Field Theory ◽  
Tight Binding ◽  
Mean Field ◽  
Topological Phase ◽  
Binding Model ◽  
System A ◽  
Topological Phase Transition ◽  
Topological Phases Of Matter ◽  
Electron Interactions

Abstract Electron-electron interactions can be useful for realizing new nontrivial topological phases of matter. Here, we show by means of a tight-binding model and mean field theory how electron-electron interactions can lead to a topological phase transition. By externally adding or removing electrons from the system a band inversion between two bands with dierent parity is induced. This leads to a topological nontrivial phase if spin-orbit coupling is present. Besides the toy-model illustrating this mechanism, we also propose SmB6 as a possible playground for experimentally realizing a topological phase transition by external tuning.

scholarly journals Tight-binding model investigation of the biaxial strain induced topological phase transition in GeCH3

2017 ◽  
Vol 96 (8) ◽  
Author(s):  
Mohsen Rezaei ◽  
Esmaeil Taghizadeh Sisakht ◽  
Farhad Fazileh ◽  
Zahra Aslani ◽  
F. M. Peeters
Keyword(s):  
Phase Transition ◽  
Tight Binding ◽  
Model Investigation ◽  
Topological Phase ◽  
Tight Binding Model ◽  
Biaxial Strain ◽  
Binding Model ◽  
Topological Phase Transition

Study of electron-phonon coupling and its effect on electrical resistivity in HF systems

2019 ◽  
Vol 33 (04) ◽  
pp. 1950012
Author(s):  
P. C. Baral
Keyword(s):  
Electrical Resistivity ◽  
Mean Field Theory ◽  
Tight Binding ◽  
Harmonic Approximation ◽  
Mean Field ◽  
Graphical Analysis ◽  
Kondo Lattice ◽  
Model Parameters ◽  
Binding Model ◽  
Model Hamiltonian

In this work, we report on theoretical study of the effect of electron-phonon (EP) interaction in THz frequency and temperature dependence of the electrical resistivity in heavy fermion (HF) systems. For this purpose, a model Hamiltonian is considered which consists of the Heisenberg type exchange interaction between localized moments and a tight binding model called the Kondo lattice model (KLM). The effect of EP coupling on electrical resistivity is presented by considering phonon interaction to bare f-electrons, band electrons and to the hybridization between band and f-electrons as a perturbed term. The phonon Hamiltonian in harmonic approximation is also included. The model Hamiltonian is solved by employing the mean-field theory (MFT) along with the Hubbard model of approximation. The temperature- and frequency-dependent electrical resistivity exhibits change in slopes at T[Formula: see text] as well as at T[Formula: see text]. The theoretical findings from the graphical analysis by varying the model parameters g[Formula: see text], g[Formula: see text] and g[Formula: see text] are compared to some of the experimental results in HF systems.

Mean field theory study of a tight-binding model for the high Tc oxides

1988 ◽  
Vol 67 (4) ◽  
pp. 349-353 ◽  
Author(s):  
X.Y. Chen ◽  
W.P. Su ◽  
C.S. Ting ◽  
D.Y. Xing
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Tight Binding ◽  
Mean Field ◽  
Tight Binding Model ◽  
Binding Model ◽  
High Tc

scholarly journals Grain-boundary topological phase transitions

2020 ◽  
Vol 117 (52) ◽  
pp. 33077-33083
Author(s):  
Kongtao Chen ◽  
David J. Srolovitz ◽  
Jian Han
Keyword(s):  
Phase Transition ◽  
Grain Boundary ◽  
Grain Growth ◽  
Kinetic Monte Carlo ◽  
Mean Field Theory ◽  
Mean Field ◽  
Polycrystalline Materials ◽  
Topological Phase ◽  
Kinetic Monte Carlo Simulations ◽  
And Migration

The formation and migration of disconnections (line defects constrained to the grain boundary [GB] plane with both dislocation and step character) control many of the kinetic and dynamical properties of GBs and the polycrystalline materials of which they are central constituents. We demonstrate that GBs undergo a finite-temperature topological phase transition of the Kosterlitz–Thouless (KT) type. This phase transition corresponds to the screening of long-range interactions between (and unbinding of) disconnections. This phase transition leads to abrupt changes in the behavior of GB migration, GB sliding, and roughening. We analyze this KT transition through mean-field theory, renormalization group theory, and kinetic Monte Carlo simulations and examine how this transition affects microstructure-scale phenomena such as grain growth stagnation, abnormal grain growth, and superplasticity.

scholarly journals Chiral $p$-wave superconductivity in twisted bilayer graphene from dynamical mean field theory

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Pahlevanzadeh ◽  
P. Sahebsara ◽  
David Sénéchal
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Tight Binding ◽  
Mean Field ◽  
Bilayer Graphene ◽  
P Wave ◽  
Dynamical Mean Field Theory ◽  
Magic Angle ◽  
Binding Model ◽  
Twisted Bilayer Graphene

We apply cluster dynamical mean field theory with an exact-diagonalization impurity solver to a Hubbard model for magic-angle twisted bilayer graphene, built on the tight-binding model proposed by Kang and Vafek [1], which applies to the magic angle 1.30^\circ1.30∘. We find that triplet superconductivity with p+ip symmetry is stabilized by CDMFT, as well as a subdominant singlet d+id state. A minimum of the order parameter exists close to quarter-filling and three-quarter filling, as observed in experiments.

ELECTRONIC STRUCTURE AND EXCHANGE IN Li2VOSiO4

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1649-1653 ◽  
Author(s):  
H. ROSNER ◽  
R. R. P. SINGH ◽  
W. E. PICKETT ◽  
W. H. ZHENG ◽  
J. OITMAA
Keyword(s):  
Heisenberg Model ◽  
Local Density ◽  
Mean Field Theory ◽  
Tight Binding ◽  
Mean Field ◽  
Recent Experimental Data ◽  
Density Approximation ◽  
Binding Model ◽  
Exchange Constants ◽  
Order Of Magnitude

Exchange couplings are calculated for Li2VOSiO4 using local density approximation (LDA). From a two band tight-binding model fitted to the LDA band structure and mapped to a Heisenberg model, the in-plane and inter-plane exchange integrals are obtained. While the sum of in-plane couplings J1+J2=9.5±1.5  K and the inter-plane coupling J⊥ ~ 0.2-0.3  K agree with recent experimental data, the ratio J2/J1 ~ 12 exceeds the reported value by an order of magnitude. Using geometrical considerations, high temperature expansions and perturbative mean field theory, we show that the LDA derived exchange constants lead to a remarkably accurate description of the properties of these materials including specific heat, susceptibility and Neél temperatures.

scholarly journals Topological phase transition between a normal insulator and a topological metal state in a quasi-one-dimensional system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Milad Jangjan ◽  
Mir Vahid Hosseini
Keyword(s):  
Phase Transition ◽  
Dimensional System ◽  
Inversion Symmetry ◽  
Topological Phase ◽  
Edge States ◽  
Zero Energy ◽  
One Dimensional ◽  
Topological Phase Transition ◽  
Metal State ◽  
Topological Metal

AbstractWe theoretically report the finding of a new kind of topological phase transition between a normal insulator and a topological metal state where the closing-reopening of bandgap is accompanied by passing the Fermi level through an additional band. The resulting nontrivial topological metal phase is characterized by stable zero-energy localized edge states that exist within the full gapless bulk states. Such states living on a quasi-one-dimensional system with three sublattices per unit cell are protected by hidden inversion symmetry. While other required symmetries such as chiral, particle-hole, or full inversion symmetry are absent in the system.

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