Effects of substrate on the magnetic properties of epitaxial TbFe2(111) films

The effects of substrate on the strains of epitaxial TbFe2(111) films, and consequently on the magnetization orientation, have been studied. Thermal strain from differential thermal contraction between substrates and the TbFe2 films is considered to be the dominant factor in determining the film strain. Therefore, Al2O3(11(2) over bar 0), MgO(111), and CaF2(111) substrates with an epitaxial W(110) buffer layer have been used to grow the TbFe2 films. The magnetization of the TbFe2 films on the Al2O3 and MgO substrates with a tensile thermal strain is in the film plane, but that on the CaF2 substrate with a compressive thermal strain is in the out-of-plane direction. An unknown soft magnetic material has been found at the interfacial region of the TbFe2 film and the W buffer layer.