Experimental results demonstrate the ability of a surface electrode pattern to produce sufficient in-plane strain in a PbZr_0.52Ti_0.48O₃ (PZT) thin film clamped by a Si substrate to control magnetism in a 1000 nm diameter Ni ring. The electrode pattern and the Ni ring/PZT thin film heterostructure were designed using a finite element based micromagnetics code. The magnetoelectric heterostructures were fabricated on the PZT film using e-beam lithography and characterized using magnetic force microscopy. Application of voltage to the electrodes moved one of the “onion” state domain walls. This method enables the development of complex architectures incorporating strain-mediated multiferroic devices.

We simulated the generation and propagation of spin waves (SWs) using two excitation methods, namely, magnetic field and voltage induced strain. A fully coupled non-linear magnetoelastic model, combining Landau–Lifshitz-Gilbert with elastodynamic equations, is used to study the propagation characteristics of SWs in magnetoelastic materials. Simulation results show that for excitation frequencies above ferromagnetic resonance (FMR), SWs excited by voltage induced strain propagate over longer distances compared to SWs excited by magnetic field. In addition, strain mediated SWs exhibit loss characteristics, which are relatively independent of the magnetic losses (Gilbert damping). Moreover, it is also shown that strain induced SWs can also be excited at frequencies below FMR.

A micromagnetic and elastodynamic finite element model is used to compare the 180° out-of-plane magnetic switching behavior of CoFeB and Terfenol-D nanodots with perpendicular magnetic easy axes. The systems simulated here consist of 50 nm diameter nanodots on top of a 100 nm-thick PZT (Pb_y[Zr_xTi_1-x]O₃) thin film, which is attached to a Si substrate. This allows voltage pulses to induce strain-mediated magnetic switching in a magnetic field free environment. Coherent and incoherent switching behaviors are observed in both CoFeB and Terfenol nanodots, with incoherent flipping associated with larger or faster applied switching voltages. The energy to flip a Terfenol-D memory element is an ultralow 22 aJ, which is 3–4 orders more efficient than spin-transfer-torque. Consecutive switching is also demonstrated by applying sequential 2.8 V voltage pulses to a CoFeB nanodot system with switching times as low as 0.2 ns.

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.

This study provides numerical simulations for deterministic 360° magnetization rotation of the transverse domain walls in a nickel nano-ring (outer diameter: 500 nm, inner diameter: 300 nm, and thickness: 10 nm) on a lead zirconate titanate (Pb[Zr_xTi_1-x]O₃ 0 < x < 1) (PZT) thin film (500 nm) deposited onto a Si substrate with surface patterned electrodes. Two alternative electrode architectures are studied, namely, a 4-electrode and a 6-electrode configuration. The 4-electrode configuration relies on magnetization dynamics to produce an overshoot coupled with proper timing control of the voltage applied to achieve 360° magnetization rotation. In contrast, the 6-electrode configuration only requires sequential voltage application to successive pairs of electrodes and thus can be operated at quasi-static speeds and does not rely on magnetization dynamics to achieve 360° magnetization rotation. These analytical models provide support for developing new devices such as nanoscale multiferroic driven electromagnetic motors.

A 400 MHz magnetoelectric (ME) Lamb wave antenna design to function in the medical implant communication service band is proposed. The antenna employs a heterostructure of piezoelectric and magnetostrictive membranes to acoustically excite standing shear bulk wave and radiate as a magnetic dipole. Multiphysics finite element analysis simulations are performed for transmission and reception modes. In these simulations, three aspects are investigated: piezoelectricity, micromagnetic precession, and magnetic dipole radiation. An experimental demonstration of the antenna is also conducted and shows mechanical resonance with a Q-factor of 500 and ME coupling. These results indicate that the design can be operated in zero-order antisymmetric (A0) mode as a tunable oscillator or sensor. This ME approach provides a solution to the miniaturization problem of traditional current-based implantable antennas.