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We study in experiment and with computer simulation the free energy and the kinetics of vacancy and interstitial defects in two-dimensional dipolar crystals. The defects appear in different local topologies which we characterize by their…

Soft Condensed Matter · Physics 2015-06-23 Wolfgang Lechner , David Polster , Georg Maret , Christoph Dellago , Peter Keim

A band gap for electronic states in crystals governs various properties of solids, such as transport, optical and magnetic properties. Its estimation and control have been an important issue in solid state physics. The band gap can be…

Mesoscale and Nanoscale Physics · Physics 2017-05-16 Shuichi Murakami , Motoaki Hirayama , Ryo Okugawa , Takashi Miyake

In this paper, we investigate the edge-Wiener index, the Szeged index, the edge-Szeged index, and the PI index, which are some of the most studied distance-based topological indices. As the main result we show that for benzenoid systems…

Combinatorics · Mathematics 2018-08-28 Matevž Črepnjak , Niko Tratnik

The classification of topological states of matter depends on spatial dimension and symmetry class. For non-interacting topological insulators and superconductors the topological classification is obtained systematically and nontrivial…

Strongly Correlated Electrons · Physics 2013-06-05 Xiao-Liang Qi

Two-dimensional topological insulators are characterized by gapped bulk states and gapless helical edge states, i.e. time-reversal symmetric edge states accommodating a pair of counter-propagating electrons. An external magnetic field…

Mesoscale and Nanoscale Physics · Physics 2012-04-02 G. Tkachov , E. M. Hankiewicz

Symmetry plays an important role in the topological band theory to remedy the eigenstates' gauge obstruction at the cost of a symmetry anomaly and zero-energy boundary modes. One can also make use of the symmetry to enumerate the…

Strongly Correlated Electrons · Physics 2021-02-25 Arpit Raj , Nepal Banerjee , Tanmoy Das

One of the hallmarks of topological insulators is the correspondence between the value of its bulk topological invariant and the number of topologically protected edge modes observed in a finite-sized sample. This bulk-boundary…

Mesoscale and Nanoscale Physics · Physics 2021-05-04 Ana Silva , Jasper van Wezel

Topological states of matter are robust quantum phases, characterised by propagating or localised edge states in an insulating bulk. Topological boundary states can be triggered by various mechanisms, for example by strong spin-orbit…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 S. E. Freeney , J. J. van den Broeke , A. J. J. Harsveld van der Veen , I. Swart , C. Morais Smith

An important aspect in categorizing topological phases is whether the system is spinless or spinful, given that these classes exhibit distinct symmetry algebras, leading to disparate topological classifications. By utilizing the projective…

Quantum Gases · Physics 2026-01-21 Xiaofan Zhou , Suotang Jia , Jian-Song Pan

The boundary of a fractionalized topological phase can be gapped by condensing a proper set of bosonic quasiparticles. Interestingly, in the presence of a global symmetry, such a boundary can have different symmetry transformation…

Strongly Correlated Electrons · Physics 2016-07-01 Fiona Burnell , Xie Chen , Alexei Kitaev , Max Metlitski , Ashvin Vishwanath

We propose a class of topological superconductivity in which the pairing order is $\mathbb{Z}_2$ topologically obstructed in a three-dimensional time-reversal invariant system. When two Fermi surfaces are related by time-reversal and mirror…

Superconductivity · Physics 2020-11-17 Canon Sun , Yi Li

Topological indices are graph invariants numeric quantities, which are utilized by researchers to analyze a variety of physiochemical aspects of molecules. The goal of developing topological indices is to give each chemical structure a…

Combinatorics · Mathematics 2022-12-09 Sohan Lal , Karnika Sharma , Vijay Kumar Bhat

The description of interactions in strongly-correlated topological phases of matter remains a challenge. Here, we develop a stochastic functional approach for interacting topological insulators including both charge and spin channels. We…

Strongly Correlated Electrons · Physics 2021-08-18 Joel Hutchinson , Philipp W. Klein , Karyn Le Hur

We study the bulk-edge correspondence in topological insulators by taking Fu-Kane spin pumping model as an example. We show that the Kane-Mele invariant in this model is Z2 invariant modulo the spectral flow of a single-parameter family of…

Mesoscale and Nanoscale Physics · Physics 2017-02-22 Yue Yu , Yong-Shi Wu , Xincheng Xie

Second-order topological insulators and superconductors have a gapped excitation spectrum in bulk and along boundaries, but protected zero modes at corners of a two-dimensional crystal or protected gapless modes at hinges of a…

Mesoscale and Nanoscale Physics · Physics 2018-07-05 Max Geier , Luka Trifunovic , Max Hoskam , Piet W. Brouwer

We construct a general theory of $Z_2$ topological phase transitions in two-dimensional systems with time-reversal symmetry. We investigate the possibilities of $Z_2$ topological phase transitions at band inversions at all high-symmetry…

Mesoscale and Nanoscale Physics · Physics 2023-03-13 Ren Sasaki , Yutaro Tanaka , Shuichi Murakami

The topology of insulators is usually revealed through the presence of gapless boundary modes: this is the so-called bulk-boundary correspondence. However, the many-body wavefunction of a crystalline insulator is endowed with additional…

Mesoscale and Nanoscale Physics · Physics 2021-01-08 Sander H. Kooi , Guido van Miert , Carmine Ortix

The past decades have witnessed a transformation in characterizing condensed matter systems with topology. Aided by a refined understanding of topological band structures with crystalline symmetries that has emerged recently, many…

Materials Science · Physics 2021-10-12 Lin-Lin Wang , Hoi Chun Po , Robert-Jan Slager , Ashvin Vishwanath

Topology is a powerful tool for categorizing magnetization textures by defining a topological index in both two-dimensional (2D) systems, such as thin films or curved surfaces, and in 3D bulk systems. In the emerging field of 3D…

We propose a new method to numerically compute the $\mathbb{Z}_2$ indices for disordered topological insulators in Kitaev's periodic table. All of the $\mathbb{Z}_2$ indices are known to be derived from the index formulae which are…

Mesoscale and Nanoscale Physics · Physics 2017-12-13 Yutaka Akagi , Hosho Katsura , Tohru Koma