Growth diagram and magnetic properties of hexagonal LuFe2O4thin films

A growth diagram of Lu-Fe-O compounds on MgO (111) substrates using pulsed laser deposition is constructed based on extensive growth experiments. The LuFe${}_{2}$O${}_{4}$ phase can only be grown in a small range of temperature and O${}_{2}$ pressure conditions. An understanding of the growth mechanism of Lu-Fe-O compound films is offered in terms of the thermochemistry at the surface. Superparamagnetism is observed in the LuFe${}_{2}$O${}_{4}$ film and is explained in terms of the effect of the impurity hexagonal LuFeO${}_{3}$ (h-LuFeO${}_{3})$ phase and structural defects.