Investigations On Magnetoelectric Coupling Effects And Applications Based On Asymmetric PZT Substrate

With the continuous development of science and technology, tunable magnetic devices become more and more pressing. Tunability of tranditional magnetic devices is achieved either by mechanical tuning bias magnet（s） or by adjusting the electric currents in solenoids/electromagnets, which makes the devices bulky, energy consuming, slow, and noisy. The study of magnetoelectric materials witch have magnetic coupling effect provides a new approach to solve this problem, that is uses electric voltages instead of magnetic fields generated by electromagnets or solenoid coils to adjust the magnetic devices. Therefore, the study on magnetoelectric coupling effect, to achieve the regulation, in particular non-volatile regulation of magnetic properties by electric voltage, has extraordinary practical significance.In this paper, ferromagnetic/piezoelectric laminated structure is chosen as the basic structure to form the magnetoelectric composite, selecting a PZT ceramic which is specific and has large piezoelectric coefficient as the piezoelectric layer. Wherein the strain-electric field （S-E） curve of that PZT exhibits a significant asymmetry, by the way of applying a different voltage pulses, it can be in one of three residual strain state A, C, D（as shown in appendix Ⅱ）, called strain memory effect. In this paper, we realize FeCoB/PZT, FeSiBC/PZT by depositing FeCoB, FeSiBC ferromagnetic films on the PZT substrate though magnetron sputtering respectively, and Metglas/PZT by bonding. By applying different impulse electric field, we get 14.8Oe,21Oe and 15.5Oe of equivalent magnetic field in FeCoB, FeSiBC, Metglas respectively. In Metglas/PZT, by applying different continuous electric field,37Oe of equivalent magnetic field we can get.In particular, we observed "pinning" phenomenon of magnetization in FeSiBC/PZT, that is applying a certain level of continuous electric field or impulse electric field on the PZT, the magnetization of FeSiBC is the same almost. According to this phenomenon, we believe that the coupling mechanism of FeSiBC/PZT fabricated by magnetron sputtering is not only strain-mediated, but also some other mechanisms work together. The Metglas/PZT adhesively prepared is totally dependent on the strain-mediated to achieve magnetoelectric coupling.Finally, we use Metglas/PZT as the core, fabricate a voltage tunable inductor device.In the case of 1kHz,we achieved 176.7%((Lmax-L_min)/L_min)of inductance by electric voltage.At the same time,three non-volatile inductance could be realized through applying different impulse electric field,the tunability of inductance is 32% （（LC-L_A）/L_A）and 38%（（LD-L_A）/L_A）.