Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance.

Changjiang Liu,Timothy A Peterson,Gordon Stecklein,Chad C Geppert,Paul A Crowell,Kevin D Christie,Sahil J Patel,Chris J Palmstrøm

doi:10.1038/ncomms10296

Changjiang Liu, Timothy A Peterson + Show 6 more

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https://doi.org/10.1038/ncomms10296

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Abstract

A distinguishing feature of spin accumulation in ferromagnet–semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this approach enables a measurement of short spin lifetimes (<100 ps), a regime that is not accessible in semiconductors using traditional Hanle techniques.

Highlights

A distinguishing feature of spin accumulation in ferromagnet–semiconductor devices is its precession in a magnetic field
We introduce here a detection technique that utilizes the precession of the magnetization under ferromagnetic resonance (FMR) to dynamically detect the spin accumulation in a SC
In summary, we have demonstrated a technique based on FMR to measure spin accumulation in FM–SC devices

Summary

Introduction

A distinguishing feature of spin accumulation in ferromagnet–semiconductor devices is its precession in a magnetic field This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. The narrow FMR linewidth and the sensitivity to both the precession of the magnetization in the ferromagnet (FM) as well as the dynamics of the spin accumulation in the SC provide an immunity to the field-dependent backgrounds that affect Hanle measurements, in the 3T case. We show that this FMR-based spin detection technique enables one to determine the spin relaxation rate in GaAs at room temperature, at which an ordinary Hanle curve cannot be measured

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