Seminário de Matéria Condensada - 05/04/2018, 11:00, Sala 426 (Torre Nova)

The current induced spin torque has been a major topic in thin film spintronics, due to its tremendous applications in magnetic memory devices with low power consumption. Recently, it is discovered that the spin Hall effect in the current-in-plane geometry can be used to generate a spin torque in prototype metal/ferromagnet bilayer thin films, such as Pt/Co or Ta/Co of about 10nm thickness. Despite the simplicity of these thin films, the precise description for the experimentally observed spin torque actually involves a variety of complicatedly intertwined mechanisms. I will present a theory that incorporates both the spin Hall effect spin transfer torque (SHE-STT) due to SHE-induced spin injection, and the spin-orbit torque (SOT) due to spin-orbit coupling induced spin accumulation. In particular, we uncover that the SHE induced spin voltage and the interface spin current are mutually dependent, hence are solved in a self-consistent manner. In addition, the spin transport mediated by the quantum well states may be responsible for the experimentally observed rapid variation of the spin torque with respect to the thickness of the ferromagnet.