Hanle Effect near Boundaries

TL;DR

This paper investigates how the Hanle effect behaves near boundaries in diffusive samples, revealing spatial dependence and shorter apparent spin lifetimes close to the boundary due to boundary-generated spins.

Contribution

It demonstrates that the Hanle curve varies spatially near boundaries when spins are generated by the extrinsic spin Hall effect, affecting the interpretation of spin lifetime measurements.

Findings

Hanle curve is spatially dependent near boundaries.

Apparent spin lifetime is shorter near the boundary.

Boundary-generated spins influence spin relaxation measurements.

Abstract

The Hanle effect describes suppression of spin polarization due to precession in a magnetic field. This is a standard spintronics tool and it gives access to the spin lifetime of samples in which spins are generated homogeneously. We examine the Hanle effect when spins are generated at a boundary of a diffusive sample by the extrinsic spin Hall effect. We show that the Hanle curve is spatially dependent and that the "apparent" spin lifetime, given by its inverse half-width, is shorter near the boundary even if the spin relaxation rate is homogenous.