5d transition metal oxide IrO2 as a material for spin current detection

TL;DR

This paper demonstrates that IrO2, a 5d transition metal oxide, exhibits a significantly larger spin Hall resistivity than noble metals, making it a promising material for spin current detection in spintronics.

Contribution

The study introduces IrO2 as a highly effective spin-current detector material with a large spin Hall resistivity, surpassing traditional noble metals and alloys.

Findings

IrO2 shows a giant rho_SH of ~38 microohm cm at room temperature.

IrO2's spin Hall resistivity is an order of magnitude larger than noble metals.

IrO2's properties are comparable to atomic layer thin films of W and Ta.

Abstract

Devices based on a pure spin current (a flow of spin angular momentum) have been attracting increasing attention as key ingredients for low-dissipation electronics. To integrate such spintronics devices into charge-based technologies, an electric detection of spin current is essential. Inverse spin Hall effect converts a spin current into an electric voltage through spin-orbit coupling. Noble metals such as Pt and Pd, and also Cu-based alloys, owing to the large direct spin Hall effect, have been regarded as potential materials for a spin-current injector. Those materials, however, are not promising as a spin-current detector based on inverse spin Hall effect. Their spin Hall resistivity rho_SH, representing the performance as a detector, is not large enough mainly due to their low charge resistivity. Here we demonstrate that heavy transition metal oxides can overcome such limitations inherent to metal-based spintronics materials. A binary 5d transition metal oxide IrO2, owing to its large resistivity as well as a large spin-orbit coupling associated with 5d character of conduction electrons, was found to show a gigantic rho_SH ~ 38 microohm cm at room temperature, one order of magnitude larger than those of noble metals and Cu-based alloys and even comparable to those of atomic layer thin film of W and Ta.