Spin Transfer Torque in Nanomagnets Jiang Xao School of Physics, Georgia Tech   Spin transfer torque is a quantum mechanical effect where the flow of electric current can induce magnetization rotation, magnetization precession, and magnetization switching in ultra-small ferromagnets. I describe the basic origin of spin-transfer and discuss its effects in nanostructures composed of single domain ferromagnets and in spin spirals and magnetic domain walls where the magnetization varies continuously in space. Semi-classical reasoning contributes substantially to understanding the effects that are observed and the effects we calculate.