  The spin Hall effect and its inverse play key roles in spintronic devices
since they allow conversion of charge currents to and from spin currents. The
conversion efficiency strongly depends on material details, such as the
electronic band structure and the nature of impurities. Here we show an anomaly
in the inverse spin Hall effect in weak ferromagnetic NiPd alloys near their
Curie temperatures with a shape independent of material details, such as Ni
concentrations. By extending Kondo's model for the anomalous Hall effect, we
explain the observed anomaly as originating from the second-order nonlinear
spin fluctuation of Ni moments. This brings to light an essential symmetry
difference between the spin Hall effect and the anomalous Hall effect which
reflects the first order nonlinear fluctuations of local moments. Our finding
opens up a new application of the spin Hall effect, by which a minuscule
magnetic moment can be detected.
