Strain-Induced Reversible Manipulation of Orbital Magnetic Moments in Ni/Cu Multilayers on Ferroelectric BaTiO3

TL;DR

This study demonstrates a reversible, electric-field-controlled manipulation of orbital magnetic moments in Ni/Cu multilayers on BaTiO3, revealing the link between strain, orbital moments, and magnetic anisotropy for future spintronic devices.

Contribution

Developed an electric-field-induced EXMCD technique to reversibly tune interfacial strain and orbital magnetic moments in Ni/Cu/BaTiO3 multilayers, elucidating their role in magnetic anisotropy control.

Findings

Reversible modulation of orbital magnetic moments via electric field.

Correlation between strain, orbital moments, and magnetic anisotropy.

Reversible switching between perpendicular and in-plane magnetization.

Abstract

Controlling magnetic anisotropy by orbital magnetic moments related to interfacial strains has considerable potential for the development of future devices using spins and orbitals. For the fundamental physics, the relationship between strain and orbital magnetic moment is still unknown, because there are few tools to probe changes of orbital magnetic moment. In this study, we developed an electric-field- (E)-induced X-ray magnetic circular dichroism (EXMCD) technique to apply E to a ferroelectric BaTiO3 substrate. We reversibly tuned the interfacial lattice constants of Ni/Cu multilayers on BaTiO3 using this technique. As the domain structures in BaTiO3 are modulated by E, EXMCD measurements reveal that the changes in the magnetic anisotropy of Ni/Cu films are induced through the modulation of orbital magnetic moments in Ni with magneto-elastic contributions. The strained Ni layer that induces the perpendicular magnetic anisotropy without E is released at E = 8 kV/cm, and in-plane magnetization also occurs. We observed that EXMCD measurements clarified the origin of the reversible changes in perpendicular magnetic anisotropy and established the relationship between macroscopic inverse magnetostriction effects and microscopic orbital moment anisotropy.