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

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(Zr_0.52 Ti_0.48 )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, E_ex,z . The in-plane strain-electric field curve (S(E_ex,z )) was carefully recorded upon successive application and removal of an out-of-plane external magnetic field, H_ex,z . The obtained S(E_ex,z ) data exhibited two main features. First, the respective in-plane piezoelectric coefficients, d(E_ex,z ) = 200–250 pm/V, show a dramatic decrease, 50–60%, upon application of a relatively low H_ex,z = 1 kOe. Second, the process is completely reversible since the initial value of d(E_ex,z ) is recovered upon removal of H_ex,z . Polarization data, P(E_ex,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%F₃O₄ system a solid basis for the development of magnetic-field-controlled PE devices.

© 2019, The Author(s).