Anomalous bias dependence of tunnel magnetoresistance in a magnetic tunnel junction

Abstract

We have fabricated a spin-polarized tunneling device based on half-metallic manganites incorporating Ba₂LaNbO₆ as an 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 a 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 strong evidence for the existence of minority-spin tunneling states at the half-metal–insulator interface.