Composite based magnetoelectric scaled devices with large output voltages

TL;DR

This study analyzes nanoscale composite magnetoelectric devices using FEM to understand strain transfer and optimize output voltage, revealing mechanisms and material choices that enable voltages over 200 mV for microelectronic integration.

Contribution

It provides a comprehensive FEM analysis of strain transfer mechanisms in scaled composite ME devices, highlighting how dimensions and materials influence voltage output.

Findings

Two distinct strain transfer mechanisms identified at scaled dimensions.

Surface clamping effects diminish with smaller pillar areas.

Large output voltages (>200 mV) achievable with optimized materials and dimensions.

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.