Magnetic properties of ultrathin NiFe and CoFe films

In this article, we report the magnetic properties of ultrathin (15-200 Ang strom) NiFe and CoFe films deposited using ion beam deposition techniques. They are symmetrically sandwiched between Ta, Cu, or Ta/Cu under and cappin g layers. NiFe and CoFe films grown between Ta/Cu and Cu/Ta bilayers exhibi t the smallest magnetic thickness loss of about 1 A. This interfacial magne tic dead layer thickness, t(0), is about 5 Angstrom for Cu-sandwiched films and about 15 Angstrom for Ta-sandwiched films. As the film thickness becom es thinner than 100 Angstrom, the magnetic properties are found to be more sensitive to the choice of material and growth environment. CoFe films show an interfacial contribution, lambda(i), about ten times larger than that f or NiFe films. Among others, NiFe and CoFe films sandwiched by Ta/Cu and Cu /Ta bilayers exhibit the smallest values of lambda(i). The magnetic anisotr opy in Ta-sandwiched CoFe films appears to be predominantly magnetoelastic in nature. (C) 2000 American Institute of Physics. [S0021-8979(00)87308-9].