Giant Extrinsic Spin Hall Effect in Platinum-Titanium Oxide Nanocomposite Films

Although the spin Hall effect provides a pathway for efficient and fast current-induced manipulation of magnetization, application of spin-orbit torque magnetic random access memory with low power dissipation is still limited to spin Hall materials with low spin Hall angles or very high resistivities. This work reports a group of spin Hall materials, Pt_{1 -x} (TiO₂ )_x nanocomposites, that combines a giant spin Hall effect with a low resistivity. The spin Hall angle of Pt_{1 -x} (TiO₂ )_x in an yttrium iron garnet/Pt_{1 -x} (TiO₂ )_x double-layer heterostructure is estimated from a combination of ferromagnetic resonance, spin pumping, and inverse spin Hall experiments. A giant spin Hall angle 1.607 ± 0.04 is obtained in a Pt_0.94 (TiO₂ )_0.06 nanocomposite film, which is an increase by an order of magnitude compared with 0.051 ± 0.002 in pure Pt thin film under the same conditions. The great enhancement of spin Hall angle is attributed to strong side-jump induced by TiO₂ impurities. These findings provide a new nanocomposite spin Hall material combining a giant spin Hall angle, low resistivity and excellent process compatibility with semiconductors for developing highly efficiency current-induced magnetization switching memory devices and logic devices.