Anomalous inverse spin Hall effect in perpendicularly magnetized Co/Pd multilayers

The spin Hall effect (SHE) and the inverse spin Hall effect (ISHE) have been widely utilized to interconvert the charge and spin currents. In them, the charge current, spin current, and spin polarization are orthogonal to each other, limiting their applications. Based on the general tensor requirement of the spin-charge conversion, additional possibilities can be introduced when the order parameter, the magnetization of a ferromagnet, is involved. We herein report the spin-charge conversion in perpendicular magnetized Co/Pd multilayers with spin pumping measurements. We unambiguously observed the anomalous inverse spin Hall effect (AISHE), where the charge current is collinear with the spin polarization. Both the sign and magnitude of AISHE can be linearly regulated by the out-of-plane magnetization of Co/Pd multilayers. Further, the observed amplitude ratio of AISHE/ISHE in spin pumping measurements is independent of the applied microwave frequency, indicating that it is a material specific parameter.