Investigation on Room Temperature Multiferroic Bi-Relaxor

Abstract

Epitaxial biferroic relaxors of formula Pb[(Zr_0.53Ti_0.47)_0.4(Fe_0.67W_0.33)_0.6]O₃ (PZTFW) were grown on (La_0.18Sr_0.82)(Al_0.59Ta_0.41)O₃ (LSAT) by pulsed laser deposition techniques. Magnetic studies were done on as-grown PZTFW/LSAT samples; whereas all electrical characterizations were carried out on conducting lanthanum strontium cobalt oxide ((La,Sr)CoO₃)- coated LSAT. X-ray diffraction patterns verify the epitaxial growth of the film. A high dielectric constant, low dielectric loss and a broad relaxor ferroelectric phase transition near room temperature were observed, however, a frequency- dependent, high-temperature; Maxwell-Wagner space charge-based phase transition was also noticed. A large and irreversible magnetization with a sharp cusp in zero-field-cooled (ZFC) magnetization with low ZFC magnetic field implies Heisenberg spin-glass behavior. Slim hysteresis loops below the freezing temperature T_f were observed which become broader at low temperature; these are typical of relaxor ferroelectrics based upon compositional disorder. Ac conductivity suggests almost frequency dependent conductivity below ferroelectric phase transition where as significant contribution of mobile charge carriers at elevated temperature.

Acknowledgments

This work was partially supported by W911NF-06-1-0183, IFN-NSF-RII 07-01-25 and DoE FG 02-08ER46526 grants.