Lead palladium zirconate titanate: A room temperature nanoscale multiferroic thin film

The discovery of single-phase multiferroic materials and the understanding of intriguing physicsof the coupling mechanisms between their spin and polarization is important for the next generation of multifunctional devices. In this work,we report dielectric, ferroelectric, and magnetization results of Pd-substituted room-temperature magnetoelectric multiferroic Pb(Zr0.20Ti0.80)0.7Pd0.3O3(PZTPd) thin films. Highly c-axis oriented PZTPd thin films were grown on {(LaAlO3)0.3(Sr2AlTaO6)0.7}(LSAT) substrates using pulsed laser deposition technique. These films were phase pure and stabilized in tetragonal phase. Atomic force microscopic studies indicated a homogeneous distribution of grains on the films’ surface with a surface roughness (RQ) of ~5.4nm. A large dielectric constant of ~1780 and a low loss tangentvalue of ~0.52 were observedat 1 kHzmeasured at room temperature. Temperature dependent dielectric studies on Pt/PZTPd/La0.7Sr0.3MnO3(LSMO) metal-insulator-metal heterostructure capacitors between 80-660 K indicated a diffused ferroelectric to paraelectric phase transition around 515 K. The polarization hysteresis loops observed at room temperature were attributed to its ferroelectric behavior. Saturated magnetization hysteresis loop with remanent magnetization of 1.54emu/cm3was obtained at room temperature. Ferromagnetic ordering in thin films was found to sustain in the entire temperature range from 5-395 K,as revealed from the constant behavior of dM/dT curve with temperature. The mixed oxidation states of palladium (Pd2+/Pd4+)dispersed in the polar Pb(Zr0.20Ti0.80)O3matrix were revealed from our high resolution x-rays photoelectron spectroscopic studies, and is ascribed to the origin of ferromagnetic ordering in the film. These findings suggest that PZTPd thin films are multiferroic (ferroelectric-ferromagnetic) at room temperature.