Tunneling magnetoresistance in (La,Pr,Ca)MnO3 nanobridges

TL;DR

This paper investigates tunneling magnetoresistance in nanobridges of (La,Pr,Ca)MnO3, revealing how phase separation influences magnetic transport properties and leads to colossal magnetoresistance effects.

Contribution

It demonstrates the ability to probe individual phase-separated regions in manganite nanobridges and observes tunneling magnetoresistance and magnetic field-induced transitions.

Findings

Tunneling magnetoresistance occurs across AFI barriers in nanobridges.

Colossal low-field magnetoresistance steps are observed near the Curie temperature.

Magnetic field induces metal-insulator transitions in discrete regions.

Abstract

The manganite (La,Pr,Ca)MnO3 is well known for its micrometer scale phase separation into coexisting ferromagnetic metallic and antiferromagnetic insulating (AFI) regions. Fabricating bridges with widths smaller than the phase separation length scale has allowed us to probe the magnetic properties of individual phase separated regions. We observe tunneling magnetoresistance across naturally occurring AFI tunnel barriers separating adjacent ferromagnetic regions spanning the width of the bridges. Further, near the Curie temperature, a magnetic field induced metal-to-insulator transition among a discrete number of regions within the narrow bridges gives rise to abrupt and colossal low-field magnetoresistance steps at well defined switching fields.