We demonstrate in situ 90° electric field-induced uniform magnetization rotation in single domain submicron ferromagnetic islands grown on a ferroelectric single crystal using x-ray photoemission electron microscopy. The experimental findings are well correlated with micromagnetic simulations, showing that the reorientation occurs by the strain-induced magnetoelectric interaction between the ferromagnetic nanostructures and the ferroelectric crystal. Specifically, the ferroelectric domain structure plays a key role in determining the response of the structure to the applied electric field, resulting in three strain-induced regimes of magnetization behavior for the single domain islands.

A unique concept for harvesting electrical energy from thermal energy is presented. A thermomechanical actuator was fabricated using ferromagnetic material. The device converts thermal energy into mechanical energy, which can be converted into electrical energy using piezoelectric materials. Magnetic force and operating frequency were measured on the device. Results show that the current power density at ΔT=50K is between 1.85 and 3.61mW∕cm2. A thermal finite element analysis model is also presented to understand the influence of thermal interface, suggesting that increases of 18.5mW∕cm2 or higher are achievable.

In this work, we report on the demonstration of voltage-driven spin wave excitation, where spin waves are generated by multiferroic magnetoelectric (ME) cell transducers driven by an alternating voltage, rather than an electric current. A multiferroic element consisting of a magnetostrictive Ni film and a piezoelectric [Pb(Mg 1/3 Nb 2/3 )O 3 ] (1Àx) -[PbTiO 3 ] x substrate was used for this purpose. By applying an AC voltage to the piezoelectric, an oscillating electric field is created within the piezoelectric material, which results in an alternating strain-induced magnetic anisotropy in the magnetostrictive Ni layer. The resulting anisotropy-driven magnetization oscillations propagate in the form of spin waves along a 5 lm wide Ni/NiFe waveguide. Control experiments confirm the strain-mediated origin of the spin wave excitation. The voltage-driven spin wave excitation, demonstrated in this work, can potentially be used for low-dissipation spin wave-based logic and memory elements. V C 2014 AIP Publishing LLC. [http://dx.

In this work, we experimentally demonstrate deterministic electrically driven, strain-mediated domain wall (DW) rotation in ferromagnetic Ni rings fabricated on piezoelectric [Pb(Mg1/3Nb2/3)O3]0.66-[PbTiO3]0.34 (PMN-PT) substrates. While simultaneously imaging the Ni rings with X-ray magnetic circular dichroism photoemission electron microscopy, an electric field is applied across the PMN-PT substrate that induces strain in the ring structures, driving DW rotation around the ring toward the dominant PMN-PT strain axis by the inverse magnetostriction effect. The DW rotation we observe is analytically predicted using a fully coupled micromagnetic/elastodynamic multiphysics simulation, which verifies that the experimental behavior is caused by the electrically generated strain in this multiferroic system. Finally, this DW rotation is used to capture and manipulate micrometer-scale magnetic beads in a fluidic environment to demonstrate a proof-of-concept energy-efficient pathway for multiferroic-based lab-on-a-chip applications.

The effect of prestress on the nonlinear dielectric (polarization) and piezoelectric (strain) response of lead zirconate–lead titanate (PZT–5H) piezoelectric ceramic is studied. The response to bipolar (−2/+2 MV/m) and unipolar (0/+2 MV/m, −0.4/+2 MV/m) electric field under constant prestress (up to 175 MPa) is experimentally evaluated. In the bipolar regime, prestress mainly influences the first non-180° process. In the unipolar regime, the dielectric and piezoelectric response achieve maximum values near 50–60 MPa because the prestress increases the number of available non-180° domains. A detailed description of the effect of the prestress on electro–mechanical response is provided in terms of non-180° domain wall motion. Based on rule of mixtures formulation, an analytical model is developed to estimate the optimum prestress value for the unipolar electric loading condition. It is found that the dielectric and piezoelectric response of the material is proportional to the volume fraction of the non-180° domains and the difference in domain wall pressure created by mechanical and electrical loads.