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Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically…

Non-symmorphic materials have recently been predicted to exhibit many different exotic features in their electronic structures. These originate from forced band degeneracies caused by the non-symmorphic symmetry, which not only creates the…

Magnetic Weyl semimetals (WSM) have recently attracted much attention due to their potential in realizing strong anomalous Hall effects. Yet, how to design such systems remains unclear. Based on first-principles calculations, we show here…

Materials Science · Physics 2025-02-21 Xiaosong Bai , Yan Wang , Wenwen Yang , Qiunan Xu , Wenjian Liu

We derive explicit anomaly-index formulas for four-dimensional Weyl fermions charged under the finite symmetries $\mathrm{Spin}\times\mathbb Z_n$ and $\mathrm{Spin}\times_{\mathbb Z_2^{\mathrm F}}\mathbb Z_{2m}^{\mathrm F}$. The strategy is…

High Energy Physics - Theory · Physics 2026-05-29 Zheyan Wan

In three-dimensional (3D) crystals, emergent particles arise when two or multiple bands contact and form degeneracy (band crossing) in the Brillouin zone. Recently a complete classification of emergent particles in 3D nonmagnetic crystals,…

Materials Science · Physics 2022-02-16 Gui-Bin Liu , Zeying Zhang , Zhi-Ming Yu , Shengyuan A. Yang , Yugui Yao

In an altermagnet, the symmetry that relates configurations with flipped magnetic moments is a rotation. This makes it qualitatively different from a ferromagnet, where no such symmetry exists, or a collinear antiferromagnet, where this…

Mesoscale and Nanoscale Physics · Physics 2024-01-04 Rafael M. Fernandes , Vanuildo S. de Carvalho , Turan Birol , Rodrigo G. Pereira

We systematically investigate the properties of bulk, surface and edge plasmons in Weyl semimetals in presence of a magnetic field. It is found that unidirectional plasmons with different properties exist on different surfaces, which is in…

Mesoscale and Nanoscale Physics · Physics 2021-12-08 Furu Zhang , Yang Gao , Wei Zhang

Topological magnons are emergent quantum spin excitations featured by magnon bands crossing linearly at the points dubbed nodes, analogous to fermions in topological electronic systems. Experimental realization of topological magnons in…

Weyl semimetals are materials where electrons behave effectively as a kind of massless relativistic particles known asWeyl fermions. These particles occur in two flavours, or chiralities, and are subject to quantum anomalies, the breaking…

Chiral magnets are an emerging class of topological matter harbouring localized and topologically protected vortex-like magnetic textures called skyrmions, which are currently under intense scrutiny as a new entity for information storage…

Recently, Wang et al. [Phys. Rev. B, 106, 195129 (2022)] challenged a widely held belief in the field of Weyl physics, demonstrating that single-pair-Weyl-points (SP-WPs) can exist in nonmagnetic spinless systems, contrary to previous…

Materials Science · Physics 2023-07-19 Guangqian Ding , Chengwu Xie , Jingbo Bai , Zhenxiang Cheng , Xiaotian Wang , Weikang Wu

Degeneracy points of parameter-dependent Hermitian matrices play a fundamental role in quantum physics, as illustrated by the concept of Berry phase in quantum dynamics, the Weyl semimetals in condensed-matter physics, and the robust…

Mesoscale and Nanoscale Physics · Physics 2023-02-17 Zoltán Guba , György Frank , Gergő Pintér , András Pályi

Magnetic Weyl semimetal (MWS) is a unique topological state with open surface Fermi arc states and other exotic transport phenomena. However, most reported MWSs show multiple pairs of Weyl points and complicated Fermi surfaces, which…

Magnetic skyrmions are localized magnetic structures that retain their shape and stability over time, thanks to their topological nature. Recent theoretical and experimental progress has laid the groundwork for understanding magnetic…

Linearly dispersing Rarita-Schwinger-Weyl (RSW) fermions featuring two Fermi velocities are the key constituents of itinerant spin-3/2 quantum materials. When doped, RSW metals sustain two Fermi surfaces (FSs), around which one fully gapped…

Superconductivity · Physics 2023-05-17 Saswata Mandal , Bitan Roy

In the presence of parallel electric and magnetic fields, the violation of separate number conservation laws for the three dimensional left and right handed Weyl fermions is known as the chiral anomaly. The recent discovery of Weyl and…

Mesoscale and Nanoscale Physics · Physics 2024-02-20 Gargee Sharma , Pallab Goswami , Sumanta Tewari

Topological semimetals with several types of three-dimensional (3D) fermion of electrons, such as Dirac fermions, Weyl fermions, Dirac nodal lines and triply degenerate nodal points have been theoretically predicted and then experimentally…

Materials Science · Physics 2018-02-28 Sami Ullah , Jiangxu Li , Ronghan Li , Qing Xie , Hui Ma , Dianzhong Li , Yiyi Li , Xing-Qiu Chen

We study the possibility of triply-degenerate points (TPs) that can be stabilized in spinless crystalline systems. Based on an exhaustive search over all 230 space groups, we find that the spinless TPs can exist at both high-symmetry points…

Mesoscale and Nanoscale Physics · Physics 2021-09-15 Xiaolong Feng , Weikang Wu , Zhi-Ming Yu , Shengyuan A. Yang

Weyl nodes have been experimentally realized in photonic, electronic, and phononic crystals. However, magnonic Weyl nodes are yet to be seen experimentally. In this paper, we propose Weyl magnon nodes in noncoplanar stacked frustrated…

Strongly Correlated Electrons · Physics 2018-03-14 S. A. Owerre

We find all Heegaard diagrams with the property "alternating" or "weakly alternating" on a genus two orientable closed surface. Using these diagrams we give infinitely many genus two 3--manifolds, each admits an automorphism whose…

Geometric Topology · Mathematics 2015-02-04 Chao Wang , Yimu Zhang