Stray-field-induced modification of coherent spin dynamics

Abstract

Electron spins in an InGaAs semiconductor quantum well are used as a magnetometer of magnetic stray fields from an array of Fe bars. Using time-resolved Faraday rotation, the coherent precession of quantum-well spins in the inhomogeneous field between the Fe bars is measured for varying external magnetic fields and different geometries of the Fe bars. Compared with reference stripes made of Au, we find an enhancement of the spin precession frequency proportional to the Fe magnetization, in line with a decrease of the spin decay time, which is attributed to the inhomogeneous magnetic stray field in the quantum-well layer. © 2007 American Institute of Physics.