Magneto-optical detection of spin accumulation under the influence of mechanical rotation

The generation of spin-polarised carriers in a non-magnetic material holds the key to realise highly efficient spintronic devices. Recently, it has been shown that the large spin-orbit coupling can generate spin-polarised currents in noble metals such as tungsten and platinum. Especially, if small samples of such metals are rotated on a plane disc in the presence of a perpendicular magnetic field, the orbital angular momentum is altered leading to a segregation of spin up and spin down electrons, i.e., a spin current in the samples. This is manifested via an induced magnetic moment on the metal. In this letter, magneto-optical Kerr effect (MOKE) is used to detect induced magnetic moments which allows remote measurements on metal samples rotating at 100~210 Hz. Our results confirm the mechanical generation of spin-polarised currents via optical detection of spin accumulation.