Surface magnetic phase transition of the double-exchange ferromagnet: Schwinger-boson mean-field study

TL;DR

This study investigates the surface magnetic phase transition in double-exchange ferromagnets using a Schwinger-boson mean-field approach, revealing surface-specific behavior relevant to magnetoresistance effects.

Contribution

It introduces a Schwinger-boson mean-field method to analyze surface magnetic transitions in metallic manganites, highlighting surface layer effects.

Findings

Surface layers are about three unit-cells wide.

Surface magnetic moments decrease faster than bulk with temperature.

Results align with experimental observations.

Abstract

The surface magnetic phase transition of a double-exchange model for metallic manganites is studied using a Schwinger-boson mean-field method. About three unit-cells wide surface layers are identified. The magnetic moment in these layers decreases more rapidly than that in the bulk when the temperature is increased. This behavior is consistent with experimental observations. We also discuss the implication of this behavior on the tunneling magnetoresistance effect using manganites and possible improvement of the magnetoresistance effect near the bulk Curie temperature.