Modification of magnetic and transport properties of manganite layers in Au/La_0.67Sr_0.33MnO_3/SrTiO_3 interfaces

TL;DR

Gold capping drastically suppresses the magnetic and conductive properties of La_0.67Sr_0.33MnO_3 thin films by forming an interfacial dead-layer, significantly altering their magnetic and transport behavior.

Contribution

This study reveals the formation of a magnetic dead-layer at Au/LSMO interfaces and its impact on magnetic and transport properties, providing new insights into interface effects in manganite films.

Findings

Resistivity increases by four orders of magnitude with Au capping.

Curie temperature decreases by 180 K due to gold deposition.

A 1.9-nm thick magnetic dead-layer forms at the interface.

Abstract

The effect of gold capping on magnetic and transport properties of optimally doped manganite thin films is studied. An extraordinary suppression of conductivity and magnetic properties occurs in epitaxial (001) La_0.67Sr_0.33MnO_3 (LSMO) films grown on SrTiO_3 upon deposition of 2 nm of Au: in the case of ultrathin films of LSMO (4 nm thick) the resistivity increases by four orders of magnitude while the Curie temperature decreases by 180 K. Zero-field 55Mn nuclear magnetic resonance reveals a significant reduction of ferromagnetic double-exchange mechanism in manganite films upon the gold capping. We find evidence for the formation of a 1.9-nm thick magnetic "dead-layer" at the Au/LSMO interface, associated with the creation of interfacial non double-exchange insulating phases.