Absence of Evidence of Electrical Switching of the Antiferromagnetic Néel Vector

Chih-Chieh Chiang^1*, Ssu-Yen Huang¹, Danru Qu², Po-Hsun Wu¹, Chia-Ling Chien^1,2,3

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Institute of Physics, Academia Sinica, Taipei, Taiwan
³Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA

* Presenter:Chih-Chieh Chiang, email:f06222067@ntu.edu.tw

Recently, the field-free switching of antiferromagnetic (AFM) Néel vector has attracted great attention. By applying an electrical current into the multi-terminal patterned structure, the recurring resistance differences have been suggested as the evidence of switching AFM Néel vector via current-induced spin-orbit torque. However, we report that a similar resistance difference occurs in the same patterned structures, even without the AFM layer [1]. Furthermore, the magnitude of the signal is strongly influenced by different normal metals and substrates. We show that when an applied writing current density is beyond the Ohmic regime, there exist unintended anisotropic thermal gradients, resulting in the recurring resistance change. Therefore, the resistance difference is not the conclusive evidence of the SOT switching of AFM Néel vector but the thermal artifacts of patterned structures on the substrate.

[1] C. C. Chiang, S. Y. Huang, D. Qu, P. H. Wu, and C. L. Chien, Phys. Rev. Lett., 123, 227203 (2019).

Keywords: Antiferromagnetism, Spin-Orbit Torque, Seebeck effect