Room temperature spin filtering in epitaxial cobalt-ferrite tunnel barriers

TL;DR

This study demonstrates room temperature spin filtering in epitaxial CoFe2O4 magnetic tunnel junctions through tunneling magnetoresistance measurements, revealing significant spin polarization effects at room temperature.

Contribution

First experimental evidence of room temperature spin filtering in epitaxial CoFe2O4 barriers using TMR measurements, confirming theoretical predictions.

Findings

TMR of -18% at 2 K

TMR of -3% at 290 K

Bias dependence matches spin filtering theory

Abstract

We report direct experimental evidence of room temperature spin filtering in magnetic tunnel junctions (MTJs) containing CoFe2O4 tunnel barriers via tunneling magnetoresistance (TMR) measurements. Pt(111)/CoFe2O4(111)/gamma-Al2O3(111)/Co(0001) fully epitaxial MTJs were grown in order to obtain a high quality system, capable of functioning at room temperature. Spin polarized transport measurements reveal significant TMR values of -18% at 2 K and -3% at 290 K. In addition, the TMR ratio follows a unique bias voltage dependence that has been theoretically predicted to be the signature of spin filtering in MTJs containing magnetic barriers. CoFe2O4 tunnel barriers therefore provide a model system to investigate spin filtering in a wide range of temperatures.