Magnetic exchange induced Weyl state in a semimetal EuCd2Sb2
Hao Su, Ben‐Chao Gong, Wujun Shi, Haifeng Yang, Hongyuan Wang, Wei Xia, Zhenhai Yu, Peng‐Jie Guo, Jinhua Wang, Linchao Ding, Liangcai Xu, Xiaokang Li, Xia Wang, Zhiqiang Zou, Na Yu, Zengwei Zhu, Yulin Chen, Zhongkai Liu, Kai Liu, Gang Li, Yanfeng Guo
Abstract
Magnetic Weyl semimetals (WSMs) bearing long-time seeking are still very rare. We have identified herein that EuCd2Sb2, a semimetal belonging to the type IV magnetic space group, hosts a magnetic exchange induced Weyl state via performing high magnetic field magnetotransport measurements and ab initio calculations. In the A-type antiferromagnetic structure, the external field larger than 3.2 T can align all Eu spins to be fully polarized along the c-axis and consequently drive EuCd2Sb2 into a spin polarized state. Magnetotransport measurements up to ∼55–60 T showed striking Shubnikov-de Hass oscillations associated with a nontrivial Berry phase. The ab initio calculations unveiled a phase transition of EuCd2Sb2 from a small gap antiferromagnetic topological insulator to a spin polarized WSM in which the Weyl points emerge along the Γ-Z path. Fermi arcs on (100) and (010) surfaces are also predicted. Meanwhile, the observed large anomalous Hall effect indicates the existence of Weyl points around the Fermi level. The results pave a way toward the realization of various topological states in a single material through the magnetic exchange manipulation.