Interface magnetism in Fe2O3/FeTiO3-heterostructures

TL;DR

This study uses density functional theory to explore the microscopic origin of interface magnetism in Fe2O3/FeTiO3 heterostructures, revealing layered arrangements, charge disproportionation, and potential for spintronics.

Contribution

It provides the first theoretical evidence linking interface magnetism to charge disproportionation and layered structures in Fe2O3/FeTiO3 heterostructures.

Findings

Layered arrangements are energetically preferred over solid solutions.

Charge mismatch is compensated by Ti4+ and Fe disproportionation.

Heterostructures exhibit halfmetallic behavior suitable for spintronics.

Abstract

To resolve the microscopic origin of magnetism in the Fe2O3/FeTiO3-system, we have performed density functional theory calculations taking into account on-site Coulomb repulsion. By varying systematically the concentration, distribution and charge state of Ti in a hematite host, we compile a phase diagram of the stability with respect to the end members and find a clear preference to form layered arrangements as opposed to solid solutions. The charge mismatch at the interface is accommodated through Ti4+ and a disproportionation in the Fe contact layer into Fe2+, Fe3+, leading to uncompensated moments in the contact layer and giving first theoretical evidence for the lamellar magnetism hypothesis. This interface magnetism is associated with impurity levels in the band gap showing halfmetallic behavior and making Fe2O3/FeTiO3 heterostructures prospective materials for spintronics applications.