BiFeO3 is a prototypical multiferroic material with large ferroelectric polarization and strong influence of the oxygen-octahedra tilts on its properties. Although properties of such material can be already efficiently studied with accurate first-principles and atomistic calculations and simulations, on the larger scale, e.g. for modelling of domain walls and their mutual interactions, it is still necessary to resort to simpler models. Among these the Landau approach has recently turned out to be extremely profitable. Although there are some parametrizations of Landau-type models [1,2,3], to our knowledge none of these is general enough to exceed limits of specific utilization for which they were developed. We present here a first-principles-based (zero temperature) parametrization of the Landau-Devonshire-type energy expansion of BiFeO3 [4] in terms of ferroelectric polarization, oxygen-octahedra tilts and mechanical strain. The scheme is based on extrapolation of the R3c structural distortion of the ground-state from the cubic reference state. This allows us to probe the energy surface for extended set of points in the parameter space and even those points, which would otherwise be difficult to access. We show that the acquired parametrization, despite simplicity of the adopted scheme, leads to tensorial properties in a sound agreement with available experimental and first-principles data. Where possible, we compare our results to the other parametrizations.
References
[1] Xue et al., Phys. Rev. B vol. 90, 220101 (2014).
[2] Popkov et al., Phys. Rev. B vol. 92, 140414 (2015).
[3] Kulagin et al., Physics of the Solid State vol. 57, 933 (2015).
[4] Marton et al., in preparation.