Critical thickness and orbital ordering in ultrathin La0.7Sr0.3MnO3 films

TL;DR

This study identifies a critical thickness of 3 unit cells for ultrathin La0.7Sr0.3MnO3 films below which they become non-metallic and non-ferromagnetic, revealing orbital ordering without reconstruction.

Contribution

It provides detailed insights into the critical thickness and orbital ordering in ultrathin La0.7Sr0.3MnO3 films, emphasizing the importance of controlled growth.

Findings

Critical thickness for non-metallic behavior is 3 unit cells.

Orbital ordering remains (x2-y2) without reconstruction.

Controlled growth enables bulk-like magnetic and transport properties.

Abstract

Detailed analysis of transport, magnetism and x-ray absorption spectroscopy measurements on ultrathin La0.7Sr0.3MnO3 films with thicknesses from 3 to 70 unit cells resulted in the identification of a lower critical thickness for a non-metallic, non-ferromagnetic layer at the interface with the SrTiO3 (001) substrate of only 3 unit cells (~12 Angstrom). Furthermore, linear dichroism measurements demonstrate the presence of a preferred (x2-y2) in-plane orbital ordering for all layer thicknesses without any orbital reconstruction at the interface. A crucial requirement for the accurate study of these ultrathin films is a controlled growth process, offering the coexistence of layer-by-layer growth and bulk-like magnetic/transport properties.