Demonstration of a pseudo-magnetization based simultaneous write and read operation in a Co ₆₀Fe ₂₀B ₂₀/Pb(Mg _1/3Nb _2/3) _0.7Ti _0.3O ₃ heterostructure

Abstract

Taking advantage of the magnetoelectric and its inverse effect, this article demonstrates strain-mediated magnetoelectric write and read operations simultaneously in Co ₆₀Fe ₂₀B ₂₀/Pb(Mg _1/3Nb _2/3) _0.7Ti _0.3O ₃ heterostructures based on a pseudo-magnetization µ ≡ m _x ²− m _y ². By applying an external DC-voltage across a (011)-cut PMN-PT substrate, the ferroelectric polarization is re-oriented, which results in an anisotropic in-plane strain that transfers to the CoFeB thin film and changes its magnetic anisotropy H _k. The change in H _k in-turn results in a 90° rotation of the magnetic easy axis for sufficiently high voltages. Simultaneously, the inverse effect is employed to read changes of the magnetic properties. The change of magnetization in ferromagnetic (FM) layer induces an elastic stress in the piezoelectric (PE) layer, which generates a PE potential that can be used to readout the magnetic state of the FM layer. The experimental results are in excellent qualitative agreement with an equivalent circuit model that considers how magnetic properties are electrically controlled in such a PE/FM heterostructure and how a back-voltage is generated due to changing magnetic properties in a self-consistent model. We demonstrated that a change of easy axis of magnetization due to an applied voltage can be directly used for information processing, which is essential for future ME based devices.