Theory of Strain-Controlled Magnetotransport and Stabilization of the Ferromagnetic Insulating Phase in Manganite Thin Films

TL;DR

Applying strain to half-doped manganites enables tuning near a metal-insulator transition, inducing colossal magnetoresistance and stabilizing ferromagnetic insulating phases, revealing new possibilities for strain engineering in magnetic materials.

Contribution

This work introduces a microscopic model showing how strain can control phase transitions and magnetotransport in manganites, including stabilizing ferromagnetic insulators.

Findings

Strain can tune manganites near a metal-insulator transition.

Tensile strain stabilizes ferromagnetic charge-ordered insulators.

Strain engineering induces colossal magnetoresistance in insulators.

Abstract

We show that applying strain on half-doped manganites makes it possible to tune the system to the proximity of a metal-insulator transition and thereby generate a colossal magnetoresistance (CMR) response. This phase competition not only allows control of CMR in ferromagnetic metallic manganites but can be used to generate CMR response in otherwise robust insulators at half-doping. Further, from our realistic microscopic model of strain and magnetotransport calculations within the Kubo formalism, we demonstrate a striking result of strain engineering that, under tensile strain, a ferromagnetic charge-ordered insulator, previously inaccessible to experiments, becomes stable.