Article
Chemistry, Multidisciplinary
Peng Li, Jinjun Ding, Steven S-L Zhang, James Kally, Timothy Pillsbury, Olle G. Heinonen, Gaurab Rimal, Chong Bi, August DeMann, Stuart B. Field, Weigang Wang, Jinke Tang, Jidong Samuel Jiang, Axel Hoffmann, Nitin Samarth, Mingzhong Wu
Summary: This study reports a genuine topological Hall effect in a TI/MI structure, where the contribution of skyrmions to the Hall effect outweighs the coexistence of magnetic phases.
Article
Chemistry, Physical
Marcio Costa, Gabriel R. Schleder, Carlos Mera Acosta, Antonio C. M. Padilha, Frank Cerasoli, Marco Buongiorno Nardelli, Adalberto Fazzio
Summary: The article introduces the discovery and application of higher-order topological insulators and explores the connection between spin Hall effect and HOTIs, proposing a new method to identify HOTIs by studying the spin Hall conductivity (SHC).
NPJ COMPUTATIONAL MATERIALS
(2021)
Article
Physics, Multidisciplinary
Ruochen Ma, Chong Wang
Summary: In this study, we demonstrate that symmetry-protected topological (SPT) phases can also be applied to average symmetries, where local quenched disorders break the symmetries but restore them upon disorder averaging. We classify and characterize a large class of average SPT phases using a decorated domain wall approach, and show that the boundary states of such phases will almost certainly be long-range entangled. We also develop a theory for generalized average SPT phases based on density matrices and quantum channels, indicating that topological quantum phenomena associated with average symmetries can be as rich as those with exact symmetries.
Article
Physics, Multidisciplinary
Yafei Ren, Cong Xiao, Daniyar Saparov, Qian Niu
Summary: The study investigates the adiabatic evolution of electronic states induced by the lattice vibration of a chiral phonon, obtaining electronic orbital magnetization in the form of a topological second Chern form. The traditional theory needs refinement by introducing a k-resolved Born effective charge and accounting for the phonon-modified electronic energy and momentum-space Berry curvature contribution. The second Chern form may diverge when a Yang's monopole is near the parameter space of interest, as demonstrated in a gapped graphene model at the Brillouin zone corner.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Wei Chen
Summary: We propose a universal topological marker that can map the topological order to lattice sites for topological insulators and superconductors with Dirac models in any dimension and symmetry class. By introducing a topological operator derived from a momentum-space universal topological invariant, we construct the topological marker by alternating projectors, position operators, and Dirac matrices. The off-diagonal elements of the topological operator yield a non-local topological marker, representing a Wannier state correlation function, which decays with a diverging correlation length at topological phase transitions. Various prototype examples are employed to demonstrate the universality of our formalism.
Article
Multidisciplinary Sciences
Qinghua Guo, Tianshu Jiang, Ruo-Yang Zhang, Lei Zhang, Zhao-Qing Zhang, Biao Yang, Shuang Zhang, C. T. Chan
Summary: Experimental observation of non-Abelian topological charges and edge states in a PT-symmetric transmission line network, along with the discovery of a non-Abelian quotient relation for the bulk-edge correspondence. This new topological property opens up possibilities for intriguing observable phenomena in the field of material science.
Article
Materials Science, Multidisciplinary
M. Koepf, S. H. Lee, Z. Q. Mao, C. A. Kuntscher
Summary: MnBi2Te4 is a promising material that could enable the quantum anomalous Hall effect, and alloy compound Mn(Bi1-xSbx)2Te4 shows significant differences in optical conductivity compared to single crystal Mn(Bi1-xSbx)2Te4.
Article
Optics
Hua Lu, Shouhao Shi, Dikun Li, Liping Hou, Shuwen Bo, Jianxu Zhao, Fajun Xiao, Dong Mao, Jianlin Zhao
Summary: Topological insulators (TIs) are a new state of matter attracting broad attention in the optics field. They have topologically-protected conducting surface states surrounding insulating bulk and exhibit prominent third-order optical nonlinearities in an ultrawide frequency range. In this study, an optical Tamm state is observed between an Sb2Te3 TI nanofilm and a 1D photonic crystal, and a self-enhancement behavior of optical nonlinearity is demonstrated in the TI nanofilm.
LASER & PHOTONICS REVIEWS
(2023)
Article
Physics, Multidisciplinary
Y. X. Zhao, Cong Chen, Xian-Lei Sheng, Shengyuan A. Yang
Summary: The study reveals the possibility of switching the two fundamental classes via Z(2) projective representations, allowing for unique topological phases to be achieved in different classes. For PT symmetry, the occurrence of this switching mechanism is demonstrated when P inverses the gauge transformation required to recover the original Z(2) gauge connections under P.
PHYSICAL REVIEW LETTERS
(2021)
Article
Multidisciplinary Sciences
P. J. Heikkinen, A. Casey, L. V. Levitin, X. Rojas, A. Vorontsov, P. Sharma, N. Zhelev, J. M. Parpia, J. Saunders
Summary: The research on surface Andreev bound states in superfluid He-3 demonstrates that they are fragile with respect to the details of surface scattering, unlike the robust surface/edge states in topological insulators and quantum Hall systems. The unexpectedly large suppression of T-c due to surface magnetic scattering leads to an increased density of low energy bound states.
NATURE COMMUNICATIONS
(2021)
Review
Physics, Condensed Matter
V Rajaji, F. J. Manjon, Chandrabhas Narayana
Summary: Pressure-induced topological quantum phase transitions (TQPTs) have attracted significant attention due to their potential technological applications. Recent studies have shown that such phase transitions can enhance the thermoelectric performance of materials, making it an important area of research for developing efficient energy harvesting materials. This review provides a comprehensive understanding of pressure-induced TQPTs from both theoretical and experimental perspectives, covering topics such as Raman signatures, important pressure-induced topological and topological crystalline insulators (TCIs), and future research directions.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Physics, Multidisciplinary
Yang Long, Baile Zhang
Summary: We develop an unsupervised classification method to categorize topological gapped systems with symmetries and construct the topological periodic table without prior knowledge of topological invariants. This data-driven strategy can consider spatial symmetries and further classify phases previously categorized as trivial. Our research introduces machine learning into topological phase classification and facilitates intelligent exploration of new phases of topological matter.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Xun-Jiang Luo, Xiao-Hong Pan, Xin Liu
Summary: The study demonstrates that the interplay between superconductors and magnetic fields based on the surface states of a weak topological insulator can lead to various helical or chiral Majorana hinge modes and even corner modes. The obtained higher-order topological superconductors can naturally behave as a TSC in DIII or D symmetry class due to their certain boundaries, surfaces, or hinges. These higher-order TSCs can be characterized by boundary topological invariants, such as surface Chern numbers or surface Z(2) topological invariants for surface TSCs.
Article
Physics, Multidisciplinary
Ari M. Turner, Erez Berg, Ady Stern
Summary: In this study, the stability of fragile topological bands protected by space-time inversion symmetry under strong electron-electron interactions is investigated. It is found that when these fragile bands are half filled, interactions can open a gap in the many-body spectrum without breaking any symmetry or mixing degrees of freedom from remote bands. The resulting ground state is not topologically ordered. The formation of fermionic bound states known as trions is crucial for this result, which may be relevant to recent experiments in magic angle twisted bilayer graphene at charge neutrality.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Penghao Zhu, Jiho Noh, Yingkai Liu, Taylor L. Hughes
Summary: In this paper, we study the scattering theory of delicate topological insulators (TIs), which are novel topological phases beyond the paradigm of the tenfold way, topological quantum chemistry, and the symmetry indicator method. We demonstrate that the phase of the reflection amplitude can probe the delicate topology by capturing a characteristic feature of a delicate TI, the returning Thouless pump. Additionally, we propose a waveguide array experiment to implement a delicate TI and measure its reflection phase, which reveals the delicate topology.
