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Higher order topological insulators are a new class of topological insulators in dimensions $\rm d>1$. These higher-order topological insulators possess $\rm (d - 1)$-dimensional boundaries that, unlike those of conventional topological…

Mesoscale and Nanoscale Physics · Physics 2021-07-05 Arijit Saha , Arun M. Jayannavar

We consider a non-Hermitian (NH) analog of a second-order topological insulator, protected by chiral symmetry, in the presence of next-nearest neighbor hopping elements to theoretically investigate the interplay beyond the first nearest…

Mesoscale and Nanoscale Physics · Physics 2024-09-16 Arnob Kumar Ghosh , Arijit Saha , Tanay Nag

Higher-order topological phases feature topologically protected boundary states in lower dimensions. Specifically, the zero-dimensional corner states are protected by the $d$th-order topology of a $d$-dimension system. In this work, we…

Mesoscale and Nanoscale Physics · Physics 2018-12-05 Linhu Li , Muhammad Umer , Jiangbin Gong

In two dimensions, intrinsic second-order topological insulators (SOTIs) are characterized by topological corner states that emerge at the intersections of distinct edges with reversed mass signs, enforced by spatial symmetries. Here, we…

Materials Science · Physics 2024-06-21 Z. J. Chen , S. G. Xu , Z. J. Xie , H. Xu , H. M. Weng

Higher-order topological insulators (HOTIs) are a newly discovered class of topological insulators which exhibit unconventional bulk-boundary correspondence. Very recently, the concept of HOTIs has been extended to aperiodic…

Mesoscale and Nanoscale Physics · Physics 2020-12-03 Chun-Bo Hua , Rui Chen , Bin Zhou , Dong-Hui Xu

Two-dimensional (2D) magnetic second-order topological insulators (SOTIs) exhibit distinct topological phases characterized by spin-polarized zero-dimensional (0D) corner states, which have garnered significant interest. However, 2D…

Materials Science · Physics 2025-02-24 Meijun Wang , Yong-An Zhong , Lei Jin , Ying Liu , Xuefang Dai , Guodong Liu , Xiaoming Zhang

The studies of topological phases of matter have been extended from condensed matter physics to photonic systems, resulting in fascinating designs of robust photonic devices. Recently, higher-order topological insulators (HOTIs) have been…

Mesoscale and Nanoscale Physics · Physics 2019-06-19 Bi-Ye Xie , Guang-Xu Su , Hong-Fei Wang , Hai Su , Xiao-Peng Shen , Peng Zhan , Ming-Hui Lu , Zhen-Lin Wang , Yan-Feng Chen

The discovery and realization of topological insulators, a phase of matter which hosts metallic boundary states when the $d$-dimension insulating bulk is confined to ($d-1$)-dimensions, led to several potential applications. Recently, it…

Second-order topological insulators (SOTI) exhibit protected gapless boundary states at their hinges or corners. In this paper, we propose a generic means to construct SOTIs in static and Floquet systems by coupling one-dimensional…

Mesoscale and Nanoscale Physics · Physics 2019-02-14 Raditya Weda Bomantara , Longwen Zhou , Jiaxin Pan , Jiangbin Gong

The higher-order topological insulator (HOTI) is a new type of topological system which has special bulkedge correspondence compared with conventional topological insulators. In this work, we propose a scheme to realize Floquet HOTI in…

Quantum Gases · Physics 2022-06-29 Ying Lei , Xi-Wang Luo , Shaoliang Zhang

We propose second-order topological insulators (SOTIs) whose lattice structure has the hexagonal symmetry $C_{6}$ in three and two dimensions. We start with a three-dimensional weak topological insulator constructed on the stacked…

Mesoscale and Nanoscale Physics · Physics 2018-07-24 Motohiko Ezawa

Conventional topological insulators support boundary states that have one dimension lower than the bulk system that hosts them, and these states are topologically protected due to quantized bulk dipole moments. Recently, higher-order…

Mesoscale and Nanoscale Physics · Physics 2020-07-24 Avik Dutt , Momchil Minkov , Shanhui Fan

We study second-order topological insulators and semimetals characterized by chiral symmetry. We investigate topological phase transitions of a model for construction of the two-dimensional second-order topological insulators protected only…

Mesoscale and Nanoscale Physics · Physics 2019-12-06 Ryo Okugawa , Shin Hayashi , Takeshi Nakanishi

Exploring novel topological matters with exotic quantum states has always been a core issue in the field of condensed matter physics, which can update the understanding of topological phases and broaden the classification of topological…

Mesoscale and Nanoscale Physics · Physics 2025-12-09 Wei Jia , Yuping Tian , Huanhuan Yang , Xiangru Kong , Zhi-Hao Huang , Wei-Jiang Gong , Jun-Hong An

Non-Hermiticity alters topology with the presence of non-Hermitian factors in topological systems. Most existing non-Hermitian topological systems derive their topological phases from Hermitian components, that is, the gain and loss of the…

Recent progress in spintronics within the paradigm of altermagnets (AMs) opens new avenues for next-generation electronic device design. Here, we establish a spin-corner locking mechanism that generates second-order topological states in…

Mesoscale and Nanoscale Physics · Physics 2025-10-20 Ning-Jing Yang , Zhigao Huang , Jian-Min Zhang

A 3d electron topological insulator (ETI) is a phase of matter protected by particle-number conservation and time-reversal symmetry. It was previously believed that the surface of an ETI must be gapless unless one of these symmetries is…

Strongly Correlated Electrons · Physics 2015-09-16 Max A. Metlitski , C. L. Kane , Matthew P. A. Fisher

While topological phases have been extensively studied in amorphous systems in recent years, it remains unclear whether the random nature of amorphous materials can give rise to higher-order topological phases that have no crystalline…

Disordered Systems and Neural Networks · Physics 2023-11-15 Yu-Liang Tao , Jiong-Hao Wang , Yong Xu

Higher-order topological insulators (HOTIs) are unique topological materials supporting edge states with the dimensionality at least by two lower than the dimensionality of the underlying structure. HOTIs were observed on lattices with…

We report the exact closed-form solutions for higher-order topological states as well as explicit energy-spectrum relationships in two-dimensional (2D) non-Hermitian multi-orbital lattices with generalized boundary conditions. These…