scholarly journals Miniband engineering and topological phase transitions in topological-insulator–normal-insulator superlattices

2021 ◽  
Vol 103 (23) ◽  
Author(s):  
G. Krizman ◽  
B. A. Assaf ◽  
G. Bauer ◽  
G. Springholz ◽  
L. A. de Vaulchier ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Topological Insulator ◽  
Topological Phase ◽  
Topological Phase Transitions

Exotic Topological Insulator States and Topological Phase Transitions in Sb2Se3–Bi2Se3 Heterostructures

ACS Nano ◽  
2012 ◽  
Vol 6 (3) ◽  
pp. 2345-2352 ◽  
Author(s):  
Qianfan Zhang ◽  
Zhiyong Zhang ◽  
Zhiyong Zhu ◽  
Udo Schwingenschlögl ◽  
Yi Cui
Keyword(s):  
Phase Transitions ◽  
Topological Insulator ◽  
Topological Phase ◽  
Topological Phase Transitions

scholarly journals Topological phases in pyrochlore thallium niobate Tl2Nb2O6+x

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Wei Zhang ◽  
Kaifa Luo ◽  
Zhendong Chen ◽  
Ziming Zhu ◽  
Rui Yu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Transitions ◽  
Topological Insulator ◽  
Continuous Solid Solution ◽  
Nodal Point ◽  
New Physics ◽  
Topological Phase ◽  
Dirac Semimetal ◽  
Topological States ◽  
Topological Phase Transitions

Abstract The discovery of new topological electronic materials brings a chance to uncover new physics. Up to now, many materials have been theoretically proposed and experimentally proved to host different kinds of topological states. Unfortunately, there is little convincing experimental evidence for the existence of topological oxides. The reason is that oxidation of oxygen leads to ionic crystal in general and makes band inversion unlikely. In addition, the realization of different topological states in a single material is quite difficult, but strongly needed for exploring topological phase transitions. In this work, using first-principles calculations and symmetry analysis, we propose that the experimentally tunable continuous solid solution of oxygen in pyrochlore Tl2Nb2O6+x (0 ≤ x ≤ 1.0) leads to various topological states. Topological insulator, Dirac semimetal, and triply degenerate nodal point semimetal can be realized in it via changing the oxygen content and/or tuning the crystalline symmetries. When x = 1, it is a semimetal with quadratic band touching point at Fermi level. It transits into a Dirac semimetal or a topological insulator depending on the in-plane strain. When x = 0.5, the inversion symmetry is spontaneously broken in Tl2Nb2O6.5, leading to triply degenerate nodal points. When x = 0, Tl2Nb2O6 becomes a trivial insulator with a narrow band gap. These topological phase transitions driven by solid solution of oxygen are unique and physically plausible due to the variation of valence state of Tl+ and Tl3+. This topological oxide will be promising for studying correlation induced topological states and potential applications.

Topological phase transitions of three-dimensional topological insulator without energy gap closing

2015 ◽  
Vol 29 (28) ◽  
pp. 1550199 ◽  
Author(s):  
Zimeng Chi ◽  
Xiaoyong Guo ◽  
Zaijun Wang ◽  
Qiang Zheng
Keyword(s):  
Phase Transitions ◽  
Topological Insulator ◽  
Energy Gap ◽  
Strong Field ◽  
Tight Binding ◽  
Three Dimensional ◽  
Flat Band ◽  
Topological Phase ◽  
Exchange Field ◽  
Topological Phase Transitions

In this paper, we demonstrate an anomalous topological phase transition without closing of bulk energy gap. We find such an effect in a model of three-dimensional (3D) topological insulator (TI) subjected to the in-plane exchange field. The energy spectrum, spin spectrum and momentum-dependent spin Chern numbers are calculated. It is shown that our system realizes both the 3D TI phase and the integer quantum Hall (QH) phase. By varying the strength of exchange field, a series of topological phase transitions takes place and in the mean time the energy gap remains open. However, the spin spectrum is closed at the transition and various topological phases are characterized with different number of nodes in spin spectrum. In a tight-binding form, the surface modes are discussed to confirm with the phase diagram. Particularly for a strong field, we find the flat band edge modes which may provide an opportunity for realizing the two-dimensional (2D) fractional QH effect on the boundary of our 3D system.

scholarly journals Creating polar antivortex in PbTiO3/SrTiO3 superlattice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adeel Y. Abid ◽  
Yuanwei Sun ◽  
Xu Hou ◽  
Congbing Tan ◽  
Xiangli Zhong ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Phase Field ◽  
Driving Force ◽  
Topological Phase ◽  
Phase Field Simulation ◽  
Topological Structures ◽  
Field Simulation ◽  
Condensed Matters ◽  
Topological Phase Transitions ◽  
Insight Into

AbstractNontrivial topological structures offer a rich playground in condensed matters and promise alternative device configurations for post-Moore electronics. While recently a number of polar topologies have been discovered in confined ferroelectric PbTiO3 within artificially engineered PbTiO3/SrTiO3 superlattices, little attention was paid to possible topological polar structures in SrTiO3. Here we successfully create previously unrealized polar antivortices within the SrTiO3 of PbTiO3/SrTiO3 superlattices, accomplished by carefully engineering their thicknesses guided by phase-field simulation. Field- and thermal-induced Kosterlitz–Thouless-like topological phase transitions have also been demonstrated, and it was discovered that the driving force for antivortex formation is electrostatic instead of elastic. This work completes an important missing link in polar topologies, expands the reaches of topological structures, and offers insight into searching and manipulating polar textures.

scholarly journals Interaction-driven topological phase transitions in fermionic SU(3) systems

2020 ◽  
Vol 101 (24) ◽  
Author(s):  
Mohsen Hafez-Torbati ◽  
Jun-Hui Zheng ◽  
Bernhard Irsigler ◽  
Walter Hofstetter
Keyword(s):  
Phase Transitions ◽  
Topological Phase ◽  
Topological Phase Transitions
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