Electron-lattice and strain effects in manganite heterostructures: the case of a single interface

TL;DR

This study models manganite heterostructures to analyze how electron-lattice interactions and strain influence the formation of metallic ferromagnetic interfaces, revealing robust metallicity at the interface despite varying interactions.

Contribution

It introduces a correlated inhomogeneous mean-field approach to study large manganite heterostructures with a single interface, highlighting the effects of electron-lattice coupling and strain.

Findings

Metallic ferromagnetic interface formation is robust against interaction variations.

Density of states remains finite at the chemical potential due to the interface.

In-plane optical conductivity shows metallic behavior, out-of-plane shows spectral weight transfer.

Abstract

A correlated inhomogeneous mean-field approach is proposed in order to study a tight-binding model of the manganite heterostructures (LaMnO3)2n/(SrMnO3)n with average hole doping x = 1/3. Phase diagrams, spectral and optical properties of large heterostructures (up to 48 sites along the growth direction) with a single interface are discussed analyzing the effects of electron-lattice anti-adiabatic fluctuations and strain. The formation of a metallic ferromagnetic interface is quite robust with varying the strength of electron-lattice coupling and strain, though the size of the interface region is strongly dependent on these interactions. The density of states never vanishes at the chemical potential due to the formation of the interface, but it shows a rapid suppression with increasing the electron-lattice coupling. The in-plane and out-of-plane optical conductivities show sharp differences since the in-plane response has metallic features, while the out-of-plane one is characterized by a transfer of spectral weight to high frequency. The in-plane response mainly comes from the region between the two insulating blocks, so that it provides a clear signature of the formation of the metallic ferromagnetic interface.