An Analysis of Piezomagnetic-Piezoelectric Semiconductor Unimorphs in Coupled Bending and Extension under a Transverse Magnetic Field

We study the response of a composite beam (unimorph) with a piezomagnetic layer and a piezoelectric semiconductor layer under a transverse magnetic field. A one-dimensional model for coupled bending and extension of the beam is derived from the three-dimensional theory. A simple and analytical solution of the model is obtained, showing that various electromechanical fields develop in the beam through piezomagnetic and piezoelectric couplings as well as semiconduction. In particular, the mobile charges in the semiconductor layer redistribute themselves under the magnetic field. A coupling coefficient is defined to describe the strength of this magneto-semiconduction coupling. The effects of physical and geometric parameters on the fields and the coupling coefficient are examined. The results are fundamental to piezotronics when magnetic effects are involved.