Structure and magnetic properties of Fe1-xNix/Cu Invar superlattices

We have prepared by sputtering techniques a series of fee [Fe1-xNix/Cu]X10 superlattices with sublayer thicknesses of 3 nm and with Ni concentrations x ranging from 0.26 to 0.54. The use of MgO single-crystal substrates and Cu sublayers in the superlattice growth ensures a well-defined fcc crystal structure in the Fe-Ni sublayers with a Ni concentration as low as 26 at. % and down to liquid helium temperatures. The magnetization of the Fe-Ni sublayers in the super lattices starts to deviate from the well-known Slater-Pauling curve at 40 at. % Ni, and continues to drop until the fcc-bcc transition is completed. A strong dependence of the magnetization on temperature was also observed for the Fe-Ni sublayers in the Invar range, consistent with the behavior of bulk Fe-Ni Invar alloys. (C) 1996 American Institute of Physics.