Strain dependence of transition temperatures and structural symmetry of BiFeO3 within the tetragonal-like structure

The influence of strain-imposed in-plane lattice symmetry on the structural and magnetic properties of tetragonal-like BiFeO3 is investigated by x-ray and elastic neutron scattering. We find that an increase in the in-plane distortion results in an increase of the Neel temperature from 313 +/- 5K to 324 +/- 3K for films grown on YAlO3 and LaAlO3, respectively. The change in magnetic ordering temperature is reproduced in three-dimensional Heisenberg Monte-Carlo simulations. These results show that strain cannot be treated as a single scalar number or simply as a direct consequence of the lattice mismatch between the film material and the substrate. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4767335]