Anomalous bias dependence of tunnel magnetoresistance in a magnetic tunnel junction

TL;DR

This paper reports an unusual bias dependence of tunnel magnetoresistance in a half-metallic magnetic tunnel junction, revealing significant density of states variation and minority spin states at the interface.

Contribution

It presents the first observation of anomalous bias dependence of TMR in a symmetric electrode junction with a single insulating barrier, highlighting interface effects.

Findings

Sharp zero bias TMR anomaly observed

Evidence of minority spin tunneling states at interface

Demonstrates drastic density of states variation near Fermi level

Abstract

We have fabricated a spin-polarized tunneling device based on half metallic manganites incorporating $Ba_{2}LaNbO_{6}$ as insulating barrier. An anomalous bias dependence of tunnel magnetoresistance (TMR) has been observed, the first of its kind in a symmetric electrode tunnel junction with single insulating barrier. The bias dependence of TMR shows an extremely sharp zero bias anomaly, which can be considered as a demonstration of the drastic density of states variation around the Fermi level of the half metal. This serves as a strong evidence for the existence of minority spin tunneling states at the half-metal insulator interface.