Novel room temperature multiferroics for random access memory elements.
We have fabricated a variety of PZT-PFW (P bZr₀.₅₂Ti₀.₄₈O₃)1-x(PbFe₂/₃W₁/₃O₃)x [PZTFWx; 0.2 < x <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 (μ₀H < 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.
Kumar
Ashok
A
Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Rico.
Katiyar
Ram S
RS
Scott
James F
JF