Role of symmetry mismatch, charge transfer and low dimensionality in the magnetic order of CaMnO$_3$/SrTiO$_3$ ultrathin heterostructures

TL;DR

This study uses ab initio calculations to explore how charge transfer, symmetry mismatch, and low dimensionality influence the magnetic and electronic properties of CaMnO₃ ultrathin films on SrTiO₃, revealing a magnetic phase transition.

Contribution

It demonstrates how interplay of charge transfer, symmetry mismatch, and strain affects magnetic order in ultrathin CaMnO₃ films, a novel insight into interface-driven magnetism.

Findings

Transition from insulating G-type to metallic A-type antiferromagnetic order.

Charge transfer and symmetry mismatch alter Mn e_g orbital occupancy.

Strain and low dimensionality significantly influence magnetic phases.

Abstract

By means of ab initio calculations, we study the effect of charge transfer and symmetry mismatch on the magnetic and electronic properties of CaMnO$_3$ ultrathin films, epitaxially grown on SrTiO$_3$ (001). We find that the interplay of these degrees of freedom, together with the low dimensionality and the strain imposed by the substrate, changes the bulk occupancy of the Mn e_$g$ orbitals, which determines the magnetic configuration of the ultrathin CMO films. A transition from an insulating G-type to a metallic A-type antiferromagnetic configuration is stabilized.