Pb(Fe0.5Nb0.5)O3 (PFN), one of the few relaxor multiferroic systems, has a G-type antiferromagnetic transition at TN = 143 K and a ferroelectric transition at TC = 385 K. By using high-resolution neutron-diffraction experiments and a total scattering technique, we paint a comprehensive picture of the long- and short-range structures of PFN: (i) a clear sign of short-range structural correlation above TC, (ii) no sign of the negative thermal expansion behavior reported in a previous study, and (iii) clearest evidence thus far of magnetoelectric coupling below TN. We conclude that at the heart of the unusual relaxor multiferroic behavior lies the disorder between Fe3+ and Nb5+ atoms. We argue that this disorder gives rise to short-range structural correlations arising from O disorder in addition to Pb displacement.
@article{arxiv.1501.00393,
title = {High-resolution structure studies and magnetoelectric coupling of relaxor multiferroic Pb(Fe$_{0.5}$Nb$_{0.5}$)O$_3$},
author = {Hasung Sim and Darren C. Peets and Sanghyun Lee and Seongsu Lee and T. Kamiyama and K. Ikeda and T. Otomo and S. -W. Cheong and Je-Geun Park},
journal= {arXiv preprint arXiv:1501.00393},
year = {2015}
}