Critical phenomena in canonical spin glass AuMn from Hall effect measurements

The extraordinary Hall resistivity ρ_ex and the magnetization M of canonical spin glass AuMn with 8 at% Mn were measured simultaneously as a function of temperature with close attention to thermal and magnetic field hysteresis. The data of ρ_ex show an anomaly at the spin glass transition temperature T_g. Moreover, the anomalous Hall coefficient R_S ∼ ρ_ex / M, which represents the chiral susceptibility of the system in the present case, also shows the anomaly. In conventional theories, the extraordinary Hall resistivity ρ_ex is represented, ρ_ex = M (A ρ + B ρ²), where ρ is the resistivity, and A and B are constants. Since ρ (T) is monotonic and smooth, the behavior of ρ_ex / M clearly indicates that another term has to be included in the expression of ρ_ex. The results can be interpreted consistently in terms of a chirality ordering model of canonical spin glasses. We argue the critical phenomena of the spin glass transition from Hall effect measurements in comparison with that from magnetization measurements.