Stray-field-induced modification of coherent spin dynamics

TL;DR

This study demonstrates how magnetic stray fields from patterned Fe stripes influence the coherent spin dynamics in an InGaAs quantum well, affecting precession frequency and decay time, with potential applications in nanoscale magnetometry.

Contribution

It introduces a method to use electron spins as local probes of magnetic stray fields from patterned ferromagnetic structures.

Findings

Stray fields from Fe stripes modify spin precession frequency.

Enhanced precession correlates with Fe magnetization.

Inhomogeneous stray fields decrease spin decay time.

Abstract

Electron spins in an InGaAs semiconductor quantum well are used as a magnetometer of magnetic stray-fields from patterned Fe stripes. Using time-resolved Faraday rotation, the coherent precession of quantum-well spins in the inhomogeneous field below the Fe stripes is measured for varying magnetic fields. Comparing 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.