Probing the spin-glass freezing transition by spin current

Recently, the enhanced pure spin current through spin fluctuations in antiferromagnetic (AF) insulators during the magnetic phase transition has attracted great attention. We report the spin current enhancement in the short-range magnetic ordered spin glass (SG) Cu_1−xMn_x alloys in this work [1]. We used the thermally driven spin current from YIG to investigate the spin frustrations and spin fluctuations in Cu_1−xMn_x alloys with various compositions, which results in a transition of the alloys from the SG state to the AF state. We show that the strongest spin fluctuation occurs at a temperature considerably higher than the magnetic critical temperature. Consequently, the thermally driven spin current can probe the spin susceptibility and the complex spin-freezing process. Furthermore, we point out the importance of the effective number of valence electrons in tailoring the spin Hall angle, which specifies the charge-to-spin conversion efficiency, in Cu_1−xMn_x alloys.

[1] Po-Hsun Wu, Yen-Chang Tu, Danru Qu, Hsia-Ling Liang, Shang-Fan Lee, and Ssu-Yen Huang , Phys. Rev. B 101, 104413 (2020)