The cation distribution in piezoelectric ferromagnetic GaFeO₃(010) thin films

GaFeO₃ is well known piezoelectric ferrimagnet where electron and spin degree of freedoms are coupled. There are four different cationic sites and the disorder in the occupation of them makes it ferrimagnet. Therefore, it is very important to study the site disorder in a specific specimen so as to understand a wide variety of ferromagnetic properties found in different GaFeO₃’s. Usually the site occupation of cations can be studied with neutron diffraction and Mösbauer spectroscopy. But, mostly they are not available for thin films.
In this work, we have developed a new procedure to identify the site occupation of the cations by measuring X-ray absorption spectroscopy and X-ray magnetic circular dichroism and comparing them with cluster calculations. We apply it to undoped and Co-doped (2%) Ga_0.6Fe_1.4O₃ thin films and successfully explain the role of doped Co ions and why they have far different ferromagnetic properties.