High resolution determination of ferromagnetic metallic limit in epitaxial La1-xCaxMnO3 films on NdGaO3

TL;DR

This study uses high-resolution techniques to determine the precise doping level at which La1-xCaxMnO3 films on NdGaO3 transition from ferromagnetic metallic to insulating, revealing the influence of substrate-induced strain.

Contribution

It provides the first detailed doping-dependent phase boundary at 1% resolution for La1-xCaxMnO3 films on NdGaO3, highlighting strain effects on phase transitions.

Findings

Films with x=0.40 show a metal-insulator transition with reduced ferromagnetic volume.

Films with x=0.41 sometimes show the transition, indicating proximity to phase boundary.

Films with x≥0.42 are insulating with significantly reduced magnetization.

Abstract

The physical properties of manganites depend strongly on sample morphology, probably due to strain. We investigate the influence of NdGaO3 substrates on the limit of the ferromagnetic-metallic phase field in La1-xCaxMnO3, doping with x=1% resolution. Films with x=0.40 show a metal-insulator transition, but the ferromagnetic volume fraction is half the spin aligned value. Films with x=0.41 are similar but the metal-insulator transition is not always seen. Films with x=0.42, 0.43, 0.44, 0.45 are insulating, and the magnetization is dramatically reduced. The observed phase boundary indicates where to search for enhanced phase separation effects that may be exploited in thin films and devices.