Assessment of Room Temperature Multiferroicity in PbPd0.3Ti0.7O3 Thin Films

Abstract

During last couple of decades, a number of researchers have been involved in discovering advanced oxide materials that possess multiferroic properties at room temperature for multifunctional applications. In this book chapter, our objective is to review the growth and characterization of palladium doped PbPd_0.3Ti_0.7O₃ (PT-Pd) single phase room temperature multiferroic thin films. Earlier Pd-doped Pb (Zr_0.20Ti_0.80)_0.70O₃ materials were first investigated in ceramic forms in our laboratory at the university of Puerto Rico by Shalini et. al. [1]. Thin films were grown, employing pulse laser deposition technique, and were characterized for their structure, magnetization, and ferroelectric properties. Highly (001) oriented PT-Pd thin films were deposited on (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.7 (LSAT) substrates with or without thin bottom layer of La_0.7Sr_0.3MnO₃ (LSMO) utilizing laser ablation processes in oxygen atmosphere. For magnetic measurements, PT-Pd deposited on LSAT substrate was used to avoid any contribution from LSMO. However, for piezo force microscopy and ferroelectric measurements, PT-Pd thin films deposited on LSMO/LSAT were chosen with LSMO as bottom electrode. Saturated magnetization M-H loops with remanent magnetization of 3.4 emu.cm^-3 and coercive field Hc of 114.5 Oe were obtained at 300 K, and PT-Pd retained the ferromagnetic ordering in the entire temperature range from 5-500 K. The origin of magnetization in the films were ascribed to Pd²⁺ and Pd⁴⁺ cations dispersed in polar PbTiO₃ ferroelectric matrix. Ferroelectric ordering in the thin films was inferred from the strong domain switching responses in its phase and amplitude image contrasts. Experimentally, our results showed that PT-Pd thin films were ferroelectric and ferromagnetic (multiferroic) at room temperature.