Evidence for a Magnetic-Field-Induced Ideal Type-II Weyl State in Antiferromagnetic Topological Insulator <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Mn</mml:mi><mml:msub><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mrow><mml:mi>Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Sb</mml:mi></mml:mrow><mml:mi>x</mml:mi></mml:msub><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi>Te</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>
Seng Huat Lee, David Graf, Lujin Min, Yanglin Zhu, Hemian Yi, Samuel Ciocys, Yuanxi Wang, Eun Sang Choi, Rabindra Basnet, Arash Fereidouni, Aaron Wegner, Yi‐Fan Zhao, Katrina Verlinde, Jingyang He, Ronald Redwing, Venkatraman Gopalan, Hugh Churchill, Alessandra Lanzara, Nitin Samarth, Cui‐Zu Chang, Jin Hu, Zhiqiang Mao
Abstract
The discovery of Weyl semimetals (WSMs) has fueled tremendous interest in condensed matter physics. The realization of WSMs requires the breaking of either inversion symmetry (IS) or time-reversal symmetry (TRS). WSMs can be categorized into type-I and type-II WSMs, which are characterized by untilted and strongly tilted Weyl cones, respectively. Type-I WSMs with breaking of either IS or TRS and type-II WSMs with solely broken IS have been realized experimentally, but a TRS-breaking type-II WSM still remains elusive. In this article, we report transport evidence for a TRS-breaking type-II WSM observed in the intrinsic antiferromagnetic topological insulator MnBi 1-x Sb x 2 Te 4 under magnetic fields. This state is manifested by the electronic structure transition caused by the spin-flop transition. The transition results in an intrinsic anomalous Hall effect and negative c-axis longitudinal magnetoresistance attributable to the chiral anomaly in the ferromagnetic phases of lightly hole-doped samples. Our results establish a promising platform for exploring the underlying physics of the long-sought, ideal TRS-breaking type-II WSM.