Novel Room Temperature Multiferroics for Random Access Memory Elements

We have fabricated a variety of PZT-PFW (P bZr(0.52)Ti(0.48)O(3))(1-x)(PbFe(2/3)W(1/3)O(3))(x) [PZTFWx; 0.2 < x < 0.4] single-phase tetragonal ferroelectrics via chemical solution deposition [polycrystalline] and pulsed laser deposition [epitaxial] onto Pt/Ti/SiO(2)/Si(100) and SrTiO(3)/Si substrates. These exhibit ferroelectricity and (weak) ferromagnetism above room temperature with strain coupling via electrostriction and magnetostriction. Application of modest magnetic field strength (mu(0)H < 1.0 T) destabilizes the long-range ferroelectric ordering and switches the polarization from approximately 22 mu C/cm(2) (0.22 C/m(2)) 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.