EPITAXIAL PbZr_(0.52)Ti_(0.48)O_3/La_(0.7)(Pb,Sr)_(0.3)MnO_3 FERROELECTRIC/CMR MEMORY OPTIMIZED FOR ROOM TEMPERATURE OPERATION

摘要

Epitaxial ferroelectric/colossal magnetoresistive PbZr_(0.52)Ti_(0.48)O_3/La_(0.7)(Pb,Sr)_(0.3)MnO_3 (PZT/LPSMO) thin film heterostructures have been grown onto SrTiO_3 single crystals by KrF pulsed laser deposition technique to fabricate nonvolatile magnetosensitive memory. Colossal magnetoresisitivity (CMR) in LPSMO film has been tailored to room temperature by compositional control to get the maximum temperature coefficient of resistivity of 7.3 percent K~(-1) @ 295 K and maximim magnetoresistivity of 27 percent @ 7 kOe and 300 K. The main processing parameters have been optimized to preserve CMR performance in LPSMO film after deposition of the top ferroelectric layer. Vertical Au/PZT/LPSMO/STO capacitor cell possesses very high dielectric permittivity about 1500 and rather low loss of 5 percent at 1 kHz, saturation polarization of 40.4 mu C/cm~2, remnant polarization of 20.6 mu C/cm~2, coercive field of 22.8 kV/cm, and no visible fatigue after 1.33 centre dot 10~8 reversals. Three top contact metals: Au, Pt, and Ta, deposited at room temperature, have been examined. As compared with Ta, Pt and Au top contacts show superior performance regarding to combined properties: high remnant and saturation polarization, low loss and no fatigue while top Ta contacts have been found to be more efficient to reduce leakage in ferroelectric film.