Simulation of inhomogeneous magnetoelastic anisotropy in ferroelectric/ferromagnetic nanocomposites

Abstract

The magnetic response of CoFe2O4/BiFeO3 (CFO/BFO) nanocomposite thin films, in which ferromagnetic CFO nanopillars are embedded in a ferroelectric BFO matrix, has been modeled by including the position-dependent magnetoelastic anisotropy of the CFO. A finite element simulation of the strain state of an arrangement of CFO pillars was performed in which the BFO matrix surrounding one or all of the pillars was subject to a piezoelectric strain. The strain transferred to the CFO pillars was calculated and transformed into a spatially varying magnetoelastic anisotropy in the CFO, and a micromagnetic model was then used to calculate the hysteresis of the pillar, which differed significantly from a macrospin model. The position-dependent anisotropy led to a complex reversal process and to a reorientation of the easy axis to the in-plane direction at sufficient applied electric fields.