Evidences of thermoelectrically driven unidirectional magnetoresistance from a single Weyl ferromagnet Co2MnGa
Bin Rong,
Lizhu Ren,
Yizhe Liu,
Bo Sun,
Jiaxin Chen,
Kie Leong Teo,
Liang Liu,
Yumeng Yang
Affiliations
Bin Rong
School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
Lizhu Ren
Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
Yizhe Liu
Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China
Bo Sun
Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China
Jiaxin Chen
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Tsung-Dao Lee Institute, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
Kie Leong Teo
Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
Liang Liu
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Tsung-Dao Lee Institute, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
Yumeng Yang
School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China
Weyl ferromagnets, with large anomalous Hall (and Nernst) effects, are an ideal playground to study unconventional transport phenomena. Here, we report a sizable unidirectional magnetoresistance with a ratio of up to 7.73 × 10−5 per current density of 1 MA cm−2 in single-layer epitaxial Co2MnGa films. Surprisingly, the nonlinear signal has an isotropic crystallographic axis dependence and scales almost linearly with the film thickness. Both features cannot be explained by the spin transport from an intrinsic band structure, but rather agree with the current induced transverse thermoelectric effect. By employing a 1D heat transfer model to account for the temperature gradient, we derived an analytical expression of this thermoelectrically driven unidirectional magnetoresistance, from which a upper bound of transverse thermopower Sxy = 3.70 ± 1.10 µV K−1 can be obtained. Our work provides direct evidences of thermoelectric voltages in the nonlinear transport signals that may be extended to other material systems as well.
