Circular domain wall motion driven by spin-polarized currents in confined square nanomagnets

The spin-transfer torque effect on the magnetization in a pillar structure has been investigated using micromagnetic simulation. The study shows that a spin-polarized dc current induces a domain wall formation from the initial inhomogeneous magnetization configuration of the square magnet and drives it to rotate in the constrained structure. Based on the result, the structure has potential use in magnetoelectronics as a rotor with no moving parts in the nanometer scale.