Strain-assisted magnetization reversal in Co/Ni multilayers with perpendicular magnetic anisotropy

TL;DR

This paper demonstrates how electric field-induced strain in ferroelectric substrates can control magnetization reversal and domain wall propagation in Co/Ni multilayers with perpendicular magnetic anisotropy, advancing low-power spintronics.

Contribution

It introduces a method to tune magnetic properties of Co/Ni multilayers via strain from ferroelectric substrates, enabling voltage-controlled magnetic switching.

Findings

Electric fields induce strain in PZT substrates, affecting magnetic films.

Strain reduces coercive field by over 30%.

Strain propagates magnetic domain walls.

Abstract

Multifunctional materials composed of ultrathin magnetic films with perpendicular magnetic anisotropy combined with ferroelectric substrates represent a new approach toward low power, fast, high density spintronics. Here we demonstrate Co/Ni multilayered films with tunable saturation magnetization and perpendicular anisotropy grown directly on ferroelectric PZT [Pb(Zr_xTi_1-x)O_3] substrate plates. Electric fields up to +/- 2 MV/m expand the PZT by 0.1% and generate at least 0.02% in-plane compression in the Co/Ni multilayered film. Modifying the strain with a voltage can reduce the coercive field by over 30%. We also demonstrate that alternating in-plane tensile and compressive strains (less than 0.01%) can be used to propagate magnetic domain walls. This ability to manipulate high anisotropy magnetic thin films could prove useful for lowering the switching energy for magnetic elements in future voltage-controlled spintronic devices.