Ferromagnetism of Pd(001) substrate induced by Antiferromagnetic CoO

TL;DR

This study demonstrates that antiferromagnetic CoO overlayers induce unexpected ferromagnetism in Pd(001) substrates through structural relaxation and local environmental effects, with potential for experimental detection and tunability.

Contribution

It reveals the mechanism by which CoO induces ferromagnetism in Pd(001), highlighting the role of lattice mismatch, structural relaxation, and environmental sensitivity of Pd's 4d electrons.

Findings

Pd exhibits spin polarization when in contact with CoO.

Ferromagnetism is enhanced by increasing CoO thickness or applying pressure.

Interfacial moments can be experimentally accessed via MOKE or XMCD.

Abstract

Our first-principles study has revealed unexpected spin polarization of the Pd(001) substrate in contact with antiferromagnetic CoO overlayers. We give an evidence that the ferromagnetism of Pd is caused by the zigzag positions of Co atoms with respect to the Pd interface, resulted from the lattice-mismatch driven structural relaxation. Thanks to the itinerant nature of its 4d electrons, we see that the ferromagnetic properties of Pd are highly sensitive to the local environment and can be enhanced further by increasing the thickness of CoO overlayer film or/and by applying an additional uniaxial pressure along c-axis exerted externally on the bottom layers of the Pd substrate. Our finding provides new functionality for the interfacial moments of the CoO/Pd system, which can be accessed experimentally, e.g., by the magneto-optical Kerr effect (MOKE) or/and by element-resolved X-ray magnetic circular dichroism (XMCD) measurement.