Emergent Spin-Filter at the interface between Ferromagnetic and Insulating Layered Oxides

TL;DR

This study reveals an interface-induced magnetization effect in magnetic tunnel junctions that causes an unexpected decrease in tunnel magnetoresistance at low temperatures, highlighting complex spin interactions at oxide interfaces.

Contribution

It demonstrates the emergence of a spin-filter effect at the interface of ferromagnetic and insulating layered oxides, affecting transport properties in a novel way.

Findings

Anomalous decrease in tunnel magnetoresistance at low temperatures.

Interface-induced Cu magnetization influences spin polarization.

Competition between positive and negative spin effects observed.

Abstract

We report a strong effect of interface-induced magnetization on the transport properties of magnetic tunnel junctions consisting of ferromagnetic manganite La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ and insulating cuprate PrBa$_{2}$Cu$_{3}$O$_{7}$. Contrary to the typically observed steady increase of the tunnel magnetoresistance with decreasing temperature, this system exhibits a sudden anomalous decrease at low temperatures. Interestingly, this anomalous behavior can be attributed to the competition between the positive spin polarization of the manganite contacts and the negative spin-filter effect from the interface-induced Cu magnetization.