Magnetically Controllable Piezotronic Responses in a Composite Semiconductor Fiber with Multiferroic Coupling Effects

Herein, a multiferroic composite semiconductor (MCS) fiber, in which the carriers transport behaviors can be effectively controlled by applying a magnetic field, is proposed. The fiber consists of two outer piezomagnetic (PM) layers, two piezoelectric (PE) layers, and a semiconducting core, and hence exhibits the comprehensive magneto-electro-semiconductive (MES) coupling effects. Based on the basic equations of multiferroic composites and the drift-diffusion model of currents in semiconductor physics, a 1D theoretical model for the laminated MCS fiber with the MES coupling effects is presented, and an analysis of the extensional deformation induced by a magnetic field is conducted. The electrons move toward one end of the fiber under the PE field resulting from the MES coupling mechanism. As a result, this leads to the redistribution of electrons in the fiber. Theoretical results show that the magnetic field as well as the initial concentration of carriers and the volume fraction of the PM or PE layer have obvious effects on the carriers transport properties and mechanical behaviors of the MCS fiber. Compared with the mechanical tuning method of piezotronics, such a magnetic field based tuning method via the MES coupling effects has some advantages because it is remote and contactless.