Novel room temperature multiferroics for random access memory elements

We have fabricated a variety of PZT-PFW (PbZr
_0.52
Ti
_0.48
O
₃
)
_{1_x}
(PbFe
_2/3
W
_1/3
O
₃
)x [PZTFWx; 0.2 <; × <; 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 (μoH <; 1.0 T) destabilizes the long-range ferroelectric ordering and switches the polarization from approximately 22 μC/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.