Probing the spin-glass freezing transition in Cu1-xMnx alloy by spin current

In this study, we used the thermally driven spin current to investigate the spin frustrations and spin fluctuations in spin-glass (SG) Cu1-xMnx alloys. Tuning the Cu1-xMnx composition results in a transition of the alloys from the SG state to the antiferromagnetic state; these states have different spin-freezing temperatures (T-f). Most spins randomly freeze at temperatures lower than the T-f of the alloy. For each alloy composition, we obtained a temperature-dependent inverse spin Hall voltage with a peak at T-p. Crucially, T-p had nearly identical composition dependence as that of T-f,, with T-p being nine times larger than T-f. Similar behavior was captured using the SG insulator, amorphous Y3Fe5O12. These results indicated that the maximum spin fluctuation in both conducting and insulating SGs occurred at temperatures considerably higher than the T-f of each. In addition, we demonstrated the importance of the effective number of valence electrons in tailoring the spin Hall angle in binary alloys.