Electronic Phase Separation in Manganite/Insulator Interfaces

TL;DR

This paper investigates how electronic and magnetic properties at manganite/insulator interfaces are affected by carrier presence, revealing phase separation phenomena and how adding layers can stabilize ferromagnetic order.

Contribution

It introduces a microscopic model to analyze interface phase separation and demonstrates how extra layers can enhance ferromagnetic stability.

Findings

Lack of carriers weakens ferromagnetic coupling at the interface.

Phase separation between ferromagnetic/metallic and antiferromagnetic/insulator phases can occur.

Adding undoped manganite layers introduces carriers that reinforce ferromagnetism.

Abstract

By using a realist microscopic model, we study the electric and magnetic properties of the interface between a half metallic manganite and an insulator. We find that the lack of carriers at the interface debilitates the double exchange mechanism, weakening the ferromagnetic coupling between the Mn ions. In this situation the ferromagnetic order of the Mn spins near the interface is unstable against antiferromagnetic CE correlations, and a separation between ferromagnetic/metallic and antiferromagnetic/insulator phases at the interfaces can occur. We obtain that the insertion of extra layers of undoped manganite at the interface introduces extra carriers which reinforce the double exchange mechanism and suppress antiferromagnetic instabilities.