Composite based magnetoelectric scaled devices with large output voltages

Abstract

In this work, we investigate the differential voltage generation arising from the direct magnetoelectric (ME) effect in nanoscale composite devices upon magnetization rotation from the magnetic ground state to an out-of-plane (OOP) configuration. These composite devices comprise a magnetostrictive ferromagnetic layer and a piezoelectric layer, mechanically coupled through strain. Using a finite element method (FEM) model, developed in COMSOL Multiphysics, we provide a comprehensive analysis of strain transfer mechanisms and resulting voltage generations. Here, the influence of dimensional and material parameters on the device performance is systematically examined. Our results indicate the presence of two distinct strain transfer mechanisms at scaled dimensions, where the device aspect ratio and the magnetic state both determine the dominant mechanism influencing the strain transfer to the piezoelectric layer. Moreover, we observed that the influence of surface clamping diminished as the pillar area was reduced. We also saw that the strain transfer to the piezoelectric layer can be enhanced by using stiffer electrodes or clamping layers. Lastly, we concluded that magnetostrictive materials with large magnetoelastic coupling constants or large Poisson ratios may strongly increase the output voltage at small dimensions. This study provides insight in the dimension and material selection when designing scaled ME pillars, with the aim of generating large output voltages. We showed that output voltages exceeding 200 mV can be achieved in scaled devices, underscoring the potential of these structures for integration into microelectronic applications.