Multiferroic epitaxial Pb(Fe_(1/2)Nb_(1/2))O_3 thin films: A relaxor ferroelectric/weak ferromagnet with a variable structure

摘要

The authors report the structural, ferroelectric, and ferromagnetic properties of Pb(Fe_(1/2)Nb_(1/2))O_3 epitaxial thin layers grown on (001), (110), and (111) SrTiO_3 substrates by pulsed-laser deposition; films were of sufficient resistivity to enable high-field P-E measurements. Findings are as follows: epitaxial strain results in (ⅰ) a dramatic increase in the spontaneous polarization P_s; (ⅱ) a lattice structure that is dependent on substrate orientation; (ⅲ) a slim-loop P-E response and relaxor ferroelectric characteristics in the dielectric constant, both of which are nearly independent of crystallographic orientation; and (ⅳ) a weak ferromagnetic moment, which is dependent on epitaxial mismatch.