Pronounced and reversible modulation of the piezoelectric coefficients by a low magnetic field in a magnetoelectric PZT-5Fe3O4 system

摘要

Composite magnetoelectric compounds that combine ferroelectricity/piezoelectricity and ferromagnetism/magnetostriction are investigated intensively for room-temperature applications. Here, we studied bulk composites of a magnetostrictive constituent, ferromagnetic Fe3O4 nanoparticles, homogeneously embedded in a ferroelectric/piezoelectric matrix, Pb(Zr0.52Ti0.48)O3 (PZT). Specifically, we focused on PZT-5%Fe3O4 samples which are strongly insulating and thus sustain a relatively high out-of-plane external electric field, Eex,z. The in-plane strain-electric field curve (S(Eex,z)) was carefully recorded upon successive application and removal of an out-of-plane external magnetic field, Hex,z. The obtained S(Eex,z) data exhibited two main features. First, the respective in-plane piezoelectric coefficients, d(Eex,z) = 200–250 pm/V, show a dramatic decrease, 50–60%, upon application of a relatively low Hex,z = 1 kOe. Second, the process is completely reversible since the initial value of d(Eex,z) is recovered upon removal of Hex,z. Polarization data, P(Eex,z), evidenced that the Fe₃O₄ nanoparticles introduced static structural disorder that made PZT harder. Taken together, these results prove that the Fe₃O₄ nanoparticles, except for static structural disorder, introduce reconfigurable magnetic disorder that modifies the in-plane S(E_ex,z) curve and the accompanying d(E_ex,z) of PZT when an external magnetic field is applied at will. The room-temperature feasibility of these findings renders the PZT-x%Fe₃O₄ system a solid basis for the development of magnetic-field-controlled PE devices.