Ground state monoclinic (M_b) phase in (110)_c BiFeO_3 epitaxial thin films

摘要

The lattice structure of (110)-oriented BiFeO_3 epitaxial thin layers has been identified by synchrotron x-ray diffraction. By using (221) and (221) peaks in the (HHL) zone, a ground state monoclinic M_b phase has been observed with lattice parameters of (β; a_m/2~(1/2) and c_m) = (89.35°; 3.985 and 3.888 A). These results demonstrate a change in phase stability from rhombohedral in bulk single crystals, to monoclinic in epitaxial thin films with two domain states whose polarization is slightly tilted away from [110] towards [111].