Intrinsic tunneling in phase separated manganites

TL;DR

This study demonstrates intrinsic electron tunneling in phase-separated manganites, revealing metastable high-resistance states and colossal resistance drops under magnetic fields, aligning with theoretical models of magnetic domain walls.

Contribution

It provides direct evidence of intrinsic tunneling across insulating regions in phase-separated manganites, linking magnetic domain walls to tunneling phenomena.

Findings

Metastable, temperature-independent high-resistance plateaus observed.

Magnetic fields extinguish intrinsic tunnel barriers, causing large resistance drops.

Results agree with theoretical predictions of magnetic domain walls in phase separation.

Abstract

We present evidence of direct electron tunneling across intrinsic insulating regions in sub-micrometer wide bridges of the phase separated ferromagnet (La,Pr,Ca)MnO$_3$. Upon cooling below the Curie temperature, a predominantly ferromagnetic supercooled state persists where tunneling across the intrinsic tunnel barriers (ITBs) results in metastable, temperature-independent, high-resistance plateaus over a large range of temperatures. Upon application of a magnetic field, our data reveal that the ITBs are extinguished resulting in sharp, colossal, low-field resistance drops. Our results compare well to theoretical predictions of magnetic domain walls coinciding with the intrinsic insulating phase.