We investigate the phase diagrams of RMn2O5 via a first-principles effective-Hamiltonian method. We are able to reproduce the most important features of the complicated magnetic and ferroelectric phase transitions. The calculated polarization as a function of temperature agrees very well with experiments. The dielectric-constant step at the commensurate-to -incommensurate magnetic phase transition is well reproduced. The microscopic mechanisms for the phase transitions are discussed.
@article{arxiv.0907.4400,
title = {First-principles modeling of multferroic RMn$_2$O$_5$},
author = {Kun Cao and Guang-Can Guo and David Vanderbilt and Lixin He},
journal= {arXiv preprint arXiv:0907.4400},
year = {2015}
}