Novel room temperature multiferroics for random access memory elements

We have fabricated a variety of PZT-PFW (PbZr_0.52Ti_0.48O₃)_{1_x}(PbFe_2/3W_1/3O₃)x [PZTFWx; 0.2 <; × <; 0.4] single-phase tetragonal ferroelectrics via chemical solution deposition [polycrystalline] and pulsed laser deposition [epitaxial] onto Pt/Ti/SiO₂/Si(100) and SrTiO₃/Si substrates. These exhibit ferroelectricity and (weak) ferromagnetism above room temperature with strain coupling via electrostriction and magnetostriction. Application of modest magnetic field strength (μoH <; 1.0 T) destabilizes the long-range ferroelectric ordering and switches the polarization from approximately 22 μC/cm² (0.22 C/m²) to zero (relaxor state). This offers the possibility of three-state logic (+P, 0, -P) and magnetically switched polarizations. Because the switching is of large magnitude (unlike the very small nanocoulomb per centimeter squared values in terbium manganites) and at room-temperature, commercial devices should be possible.