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Title: Large Negative Magnetoresistance and Quantum Oscillation in a Field-Induced Weyl Semimetal ErAuSn 

Authors:Yue Lu, Feng Zhou, Jie Chen, Mingzhe Hu, Shunye Gao, Xuekui Xi, Yong-Chang Lau, Orest Pavlosiuk, Piotr Wiśniewski, Dariusz Kaczorowski, Tian Qian, Wenhong Wang 

Journal: Advanced Functional Materials 

DOI: 10.1002/adfm.202505276   

In continuation of its research on Heusler phases and their topologically nontrivial properties, the group of Prof. Dariusz Kaczorowski, in collaboration with partners from Tiangong University, Institute of Physics of the Chinese Academy of Sciences and University of Chinese Academy of Sciences, conducted a comprehensive study of the magnetotransport properties of high-quality single crystals of ErAuSn compound.

The results of these investigation demonstrated that under an applied magnetic field, ErAuSn undergoes a transition from a topologically trivial semimetal to a topologically non-trivial Weyl semimetal, accompanied by a giant negative values of longitudinal magnetoresistance (MR) reaching up to –97% (at T = 2 K and in B = 9 T). Remarkably, unlike previously known topological semimetals, where negative MR typically requires precise alignment between current and magnetic field (due to the chiral anomaly), ErAuSn shows large negative MR that is largely independent of the magnetic field orientation. This unique behaviour is attributed to the alignment of Er magnetic moments in a magnetic field, which induces a reconstruction of the electronic band structure and gives rise to Weyl fermions. These findings are supported by both detailed analysis of Shubnikov-de Haas oscillations and first-principles electronic band structure calculations.

This discovery not only expands the catalogue of field-tunable topological materials but also opens new perspectives for designing topological materials with tunable transport properties, relevant for future applications in spintronics and quantum electronics.

This research was financially supported by the National Science Centre of Poland, project SHENG, grant no. 2021/40/Q/ST5/00066