Abstract
We investigate the phase diagrams of 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.
- Received 24 July 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.257201
©2009 American Physical Society