Transition from parallel to antiparallel magnetic state at the interface of Fe3O4/Mn3O4 superlattices (invited)

A series of ferrimagnetic/ferrimagnetic Fe3O4/Mn3O4 superlattices are grown on MgO(001) and (011) substrates by plasma-oxygen-assisted molecular beam epitaxy. The thickness of the Fe3O4 layer is 4 nm and the thickness of Mn3O4 is varied from 1 to 16 nm and the total thickness of these films is between 100 and 200 nm. The magnetization as a function of temperature and external field (parallel to the film surface) is measured in the range of 4–300 K and −50–50 kOe. The main magnetic response of the superlattices with thicker Mn3O4 layers show compensation points (∼39 K) and spin-flop phases at a high external field (>15 kOe) indicating the net moments in Fe3O4 and Mn3O4 are antiparallel at the interface. The magnetic response of the superlattices with thinner Mn3O4 layers show regular ferromagnetic hysteresis and temperature curves indicating the net moments in Fe3O4 and Mn3O4 are parallel at the interface. A transition of the magnetic coupling between Fe3O4 and Mn3O4 from antiparallel to parallel is clearl...