Strain-mediated 180° perpendicular magnetization switching of a single domain multiferroic structure

Abstract

Analytical results for a voltage induced 180° perpendicular magnetization switching in a single magnetic nanoelement are presented. This 180° switching is achieved by combining perpendicular magnetic anisotropy due to surface effects with a temporally short voltage induced strain pulse. The angular momentum of the magnetic moment results in its precession in response to an in-plane effective magnetic field induced by strain, causing it to overshoot the 90° reorientation to an in-plane equilibrium position. Removal of the strain at the peak overshoot results in a 180° magnetization switch. This process is simulated using a micromagnetic dynamic approach implemented in a finite element framework that includes shape anisotropy and perpendicular magnetic anisotropy contributions to the energy functional in addition to the exchange and magnetoelastic energy terms. Control of the energy landscape to enable the 180° switching was accomplished by controlling the film thickness, and the strain pulse amplitude and duration. A film thickness near the critical thickness for in-plane to out-of-plane equilibrium magnetization direction was used to reduce the energy barrier to switching and thus reduce the necessary strain to levels that can be achieved in ferroelectric thin films clamped by a substrate.