Temperature dependent phonon Raman scattering of highly a-axis oriented CoFe2O4 inverse spinel ferromagnetic films grown by pulsed laser deposition

Lattice vibrations of highly a-axis oriented CoFe2O4 (CFO) films have been investigated by Raman scattering in the temperature range of 80-873 K. The five phonon modes T-1g(2), T-1g(3), E-g, A(1g)(1), A(1g)(2), and their evolutions can be uniquely distinguished. It was found that an electron transfer between Co2+ and Fe3+ cations occurs in octahedral sites at about 173 K. The structure disorder in the CFO films appears with increasing the temperature, which indicates the cation migration between tetrahedral and octahedral sites. The phenomena suggest the structural transformation trend from inverse spinel to normal spinel at the elevated temperatures. (C) 2012 American Institute of Physics. [doi:10.1063/1.3683520]