d0 Ferromagnetic Interface Between Non-magnetic Perovskites

TL;DR

This study combines computational and experimental approaches to demonstrate that charge-imbalanced d0 perovskite interfaces, such as SrTiO3/KTaO3, exhibit room-temperature ferromagnetism due to high density of states and exchange interactions at oxygen orbitals.

Contribution

It reveals that hole-type d0 perovskite interfaces inherently exhibit ferromagnetism, expanding understanding of magnetic properties in non-magnetic oxides.

Findings

Ferromagnetism observed at room temperature in various d0 perovskite interfaces.

Charge imbalance induces a half-metallic 2D electron gas at the interface.

Ferromagnetic behavior is a general property of hole-type d0 perovskite interfaces.

Abstract

We use computational and experimental methods to study d0 ferromagnetism at a charge- imbalanced interface between two perovskites. In SrTiO3/KTaO3 superlattice calculations, the charge imbalance introduces holes in the SrTiO3 layer, inducing a d0 ferromagnetic half-metallic 2D electron gas at the interface oxygen 2p orbitals. The charge imbalance overrides doping by vacancies at realistic concentrations. Varying the constituent materials shows ferromagnetism to be a gen- eral property of hole-type d0 perovskite interfaces. Atomically sharp epitaxial d0 SrTiO3/KTaO3, SrTiO3 /KNbO3 and SrTiO3 /NaNbO3 interfaces are found to exhibit ferromagnetic hysteresis at room temperature. We suggest the behavior is due to high density of states and exchange coupling at the oxygen t1g band in comparison with the more studied d band t2g symmetry electron gas.