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We study the nontrivial linear magnon band crossings in the collinear antiferromagnets on the two-dimensional (2D) CaVO lattice, also realized in some iron-based superconductors such as AFe$_{1.6+x}$Se$_2$ (A = K, Rb, Cs). It is shown that…

Strongly Correlated Electrons · Physics 2018-06-22 S. A. Owerre

The pyrochlore lattice, a three-dimensional network of corner-sharing tetrahedra, is a promising material playground for correlated topological phases arising from the interplay between spin-orbit coupling (SOC) and electron-electron…

We study the topological properties of magnon excitations in three-dimensional antiferromagnets, where the ground state configuration is invariant under time-reversal followed by space-inversion ($PT$-symmetry). We prove that Dirac points…

Mesoscale and Nanoscale Physics · Physics 2017-12-20 Kangkang Li , Chenyuan Li , Jiangping Hu , Yuan Li , Chen Fang

The interband optical absorption of linearly polarised light by two-dimensional (2D) semimetals hosting tilted and anisotropic Dirac cones in the bandstructure is analysed theoretically. Super-critically tilted (type-II) Dirac cones are…

Mesoscale and Nanoscale Physics · Physics 2022-06-09 A. Wild , E. Mariani , M. E. Portnoi

We study a Dirac Harper model for moir\'e bilayer superlattices where layer antisymmetric strain periodically modulates the interlayer coupling between two honeycomb lattices in one spatial dimension. Discrete and continuum formulations of…

Mesoscale and Nanoscale Physics · Physics 2020-10-21 Abigail Timmel , E. J. Mele

SnTe is a prototypical topological crystalline insulator, in which the gapless surface state is protected by a crystal symmetry. The hallmark of the topological properties in SnTe is the Dirac cones projected to the surfaces with mirror…

Strong band engineering in two-dimensional (2D) materials can be achieved by introducing moir\'e superlattices, leading to the emergence of various novel quantum phases with promising potential for future applications. Presented works to…

Mesoscale and Nanoscale Physics · Physics 2023-03-27 Shimin Cao , Mantang Chen , Jiang Zeng , Ning Ma , Runjie Zheng , Ya Feng , Shili Yan , Jing Liu , Kenji Watanabe , Takashi Taniguchi , X. C. Xie , Jian-Hao Chen

To realize band structures with non-trivial topological properties in an optical lattice is an exciting topic in current studies on ultra cold atoms. Here we point out that this lofty goal can be achieved by using a simple scheme of shaking…

Quantum Gases · Physics 2015-06-18 Shao-Liang Zhang , Qi Zhou

We show by means of ab initio calculations and tight-binding modeling that an oxide system based on a honeycomb lattice can sustain topologically non-trivial states if a single orbital dominates the spectrum close to the Fermi level. In…

Mesoscale and Nanoscale Physics · Physics 2016-09-21 J. L. Lado , V. Pardo

Dirac semimetals associated with bulk Dirac fermions are well-known in topological electronic systems. In sharp contrast, three-dimensional (3D) Dirac phonons in crystalline solids are still unavailable. Here we perform symmetry arguments…

Materials Science · Physics 2021-05-12 Zhongjia Chen , Rui Wang , Bowen Xia , Baobing Zheng , Yuanjun Jin , Yu-Jun Zhao , Hu Xu

In this pedagogical paper we review the discrete symmetries of the Dirac equation using elementary tools, but in a comparative order: the usual 3 + 1 dimensional case and the 2 + 1 dimensional case. Motivated by new applications of the 2d…

Other Condensed Matter · Physics 2015-03-25 Emerson Sadurní , Eladio Rivera-Mociños , Alfonso Rosado

We propose and characterize a new $\mathbb{Z}_2$ class of topological semimetals with a vanishing spin--orbit interaction. The proposed topological semimetals are characterized by the presence of bulk one-dimensional (1D) Dirac Line Nodes…

Materials Science · Physics 2015-12-03 Youngkuk Kim , Benjamin J. Wieder , C. L. Kane , Andrew M. Rappe

By means of atomistic tight-binding calculations, we investigate the transport properties of vertical devices made of two incommensurately misoriented graphene layers. With a chosen transport direction (Ox-axis), we define two classes of…

Mesoscale and Nanoscale Physics · Physics 2015-12-23 Viet Hung Nguyen , Philippe Dollfus

The notion of Dirac cones, wherein two or more bands become degenerate at a certain momentum, is the starting point for the study of topological phases. Dirac cones have been thoroughly explored in fermionic systems such as graphene, Weyl…

Mesoscale and Nanoscale Physics · Physics 2020-07-15 P. Sathish Kumar , R. Ganesh

We demonstrate a new method of achieving topologically protected states in a discrete hexagonal lattice by attaching gyroscopic spinners, which bring chirality to the system. Dispersive features of this medium are investigated in detail…

Classical Physics · Physics 2018-08-15 Marta Garau , Giorgio Carta , Michael Nieves , Ian Jones , Natasha Movchan , Alexander Movchan

We propose a design of two-dimensional bi-anisotropic meta-waveguide exhibiting topologically nontrivial photonic phase and robust photonic transport. The structure proposed represents a waveguide formed by a periodic array of metallic…

Atomic scale engineering of two-dimensional materials could create devices with rich physical and chemical properties. External periodic potentials can enable the manipulation of the electronic band structures of materials. A prototypical…

Materials Science · Physics 2019-05-22 B. Feng , H. Zhou , Y. Feng , H. Liu , S. He , I. Matsuda , L. Chen , E. F. Schwier , K. Shimada , S. Meng , K. Wu

We study a non-Hermitian variant of the (2+1)-dimensional Dirac wave equation, which hosts a real energy spectrum with pairwise-orthogonal eigenstates. In the spatially uniform case, the Hamiltonian's non-Hermitian symmetries allow its…

Mesoscale and Nanoscale Physics · Physics 2023-08-09 Yun Yong Terh , Rimi Banerjee , Haoran Xue , Y. D. Chong

We present a two-band model based on periodic H\"uckel theory, which is capable of predicting the existence and position of Dirac cones in the first Brillouin zone of an infinite class of two-dimensional periodic carbon networks, obtained…

Mesoscale and Nanoscale Physics · Physics 2014-06-24 Willem Van den Heuvel , Alessandro Soncini

A three-dimensional (3D) Dirac semimetal is the 3D analog of graphene whose bulk band shows a linear dispersion relation in the 3D momentum space. Since each Dirac point with four-fold degeneracy carries a zero Chern number, a Dirac…

Mesoscale and Nanoscale Physics · Physics 2014-09-18 Bohm-Jung Yang , Naoto Nagaosa