Manipulating magnetic devices with spin-orbit torques

Magnetic devices are a leading contender for the implementation of memory and logic technologies that are non-volatile, that can scale to high density and high speed, and that do not wear out. However, widespread application of magnetic memory and logic devices will require the development of efficient mechanisms for reorienting their magnetization using the least possible current and power. Until recently, the most-efficient known mechanism for manipulating magnetization in practical device geometries was spin-transfer torque from a spin-polarized current. However, this “conventional” spin-transfer torque faces a fundamental limit in efficiency - it can be no stronger than the equivalent of one unit of hbar angular momentum transferred per unit charge in the applied current. I will discuss recent experiments which indicate that new mechanisms based on spin-orbit interactions can be used to generate current-induced torques that are orders of magnitude more efficient than this previous limit.