The control of magnetic order in nanoscale devices underpins many proposals for integrating spintronics concepts into conventional electronics. A key challenge lies in finding an energy-efficient means of control, as power dissipation remains an important factor limiting future miniaturization of integrated circuits. One promising approach involves magnetoelectric coupling in magnetostrictive/piezoelectric systems, where induced strains can bear directly on the magnetic anisotropy. While such processes have been demonstrated in several multiferroic heterostructures, the incorporation of such complex materials into practical geometries has been lacking. Here we demonstrate the possibility of generating sizeable anisotropy changes, through induced strains driven by applied electric fields, in hybrid piezoelectric/spin-valve nanowires. By combining magneto-optical Kerr effect and magnetoresistance measurements, we show that domain wall propagation fields can be doubled under locally applied strains. These results highlight the prospect of constructing low-power domain wall gates for magnetic logic devices.

Magnetic and mechanical behaviour are strongly coupled: an applied stress modifies the magnetic behaviour, and on the other hand, magnetic materials undergo a magnetisation-induced strain known as the magnetostriction strain. These coupling effects play a significant role on the overall performance of electromagnetic devices such as magnetostrictive transducers or high-performance electric machines. In order to provide engineers with accurate design tools, magneto-elastic effects must be included into constitutive laws for magnetic materials. The origin of the magneto-elastic coupling lies in the competitive contributions of stress and magnetic field to the definition of magnetic domain configurations in magnetic materials. The magnetic domain scale is then suitable to describe magneto-elastic interactions, and this is the reason why multiscale approaches based on a micro-mechanical description of magnetic domain structures have been developed in the last decades. We propose in this paper an extension of a previous anhysteretic multiscale model in order to consider hysteresis effects. This new irreversible model is fully multiaxial and allows the description of typical hysteresis and butterfly loops and the calculation of magnetic losses as a function of external magneto-mechanical loadings. It is notably shown that the use of a configuration demagnetising effect related to the initial domain configuration enables to capture the non-monotony of the effect of stress on the magnetic susceptibility. This configuration demagnetising effect is also relevant to describe the effects of stress on hysteresis losses and coercive field.

A magnetic hysteresis model is developed based on the vector generalization of Jiles-Atherton (JA) model combined with a simplified multiscale approach to take into account the effect of mechanical stress on the magnetic behavior. The model aims at representing electrical steel behavior under any loading configuration considering the magnetic field vector and the mechanical stress second-order tensor. Mechanical stress is introduced in the JA hysteresis model through the anhysteretic magnetization and a modified pinning parameter. The main properties of the model are shown under alternating and rotating applied induction, especially in terms of hysteresis losses. The differential magnetic susceptibility is derived from the model, and the implementation into a time-stepping finite-element method is detailed. Finally, a quasi-statically rotating switched reluctance motor is studied: considering different shrink-fitting conditions, the resulting stress is shown to have a significant effect on both distribution and global value of hysteresis losses.