Spin Transfer from a Ferromagnet into a Semiconductor through an Oxide barrier

TL;DR

This study investigates spin transfer in a Ni/Al2O3/n-doped Si system, revealing significant magnetoresistance at low temperatures and suggesting interface magnetic states, with a spin diffusion length of about 650 nm.

Contribution

It demonstrates spin transfer across an oxide barrier into a semiconductor and analyzes the magnetoresistance behavior in nanostructures at cryogenic temperatures.

Findings

75% magnetoresistance at 14K

Spin transfer occurs outside the tunnel resistance thresholds

Minimum resistance observed in antiparallel Ni configurations

Abstract

We present results on the magnetoresistance of the system Ni/Al203/n-doped Si/Al2O3/Ni in fabricated nanostructures. The results at temperature of 14K reveal a 75% magnetoresistance that decreases in value up to approximately 30K where the effect disappears. We observe minimum resistance in the antiparallel configurations of the source and drain of Ni. As a possibility, it seems to indicate the existence of a magnetic state at the Si/oxide interface. The average spin diffusion length obtained is of 650 nm approximately. Results are compared to the window of resistances that seems to exist between the tunnel barrier resistance and two threshold resistances but the spin transfer seems to work in the range and outside the two thresholds.