Tunable Spin Filtering through an Aluminum Nanoparticle

TL;DR

This paper demonstrates tunable spin filtering in an aluminum nanoparticle, revealing long spin relaxation times in specific quantum states, with potential implications for spintronic devices.

Contribution

It introduces a method to control spin filtering in aluminum nanoparticles and measures spin relaxation times in different quantum states.

Findings

Spin-polarized current can be tuned by magnetic field direction.

Spin relaxation time exceeds 8 ns in the ground state.

Stepwise increase in current confirms state-dependent spin relaxation.

Abstract

Spin-polarized current through an Al nanoparticle in tunnel contact with two ferromagnets is measured as a function of the direction of the applied magnetic field. The nanoparticle filters the spin of injected electrons along a direction specified by the magnetic field. The characteristic field scale for the filtering corresponds to a lower limit of $8ns$ for the spin-dephasing time. Spin polarized current versus applied voltage increases stepwise, confirming that the spin relaxation time is long only in the ground state and the low-lying excited states of the nanoparticle.