INTERFACE MAGNETISM IN PERMALLOY CU MULTILAYERS - FERROMAGNETIC-RESONANCE STUDY/

Ferromagnetic resonance has been applied to study sputtered [Permalloy /Cu](100) multilayers with Permalloy (Py) and Cu layers thicknesses 5 Angstrom < d(Py) < 40 Angstrom and 8 Angstrom < d(Cu) < 40 Angstrom, r espectively. The effective magnetization is analyzed in the vicinity o f nominal critical thicknesses of Py layers, 2 Delta d = 4.9, 7.6, and 8.3 Angstrom, at 77, 293, and 400 K, respectively. From its behavior and the temperature measurements of ferromagnetic resonance (FMR) spec tra we argue about the magnetic structure of a statistically averaged interface between Py and Cu: At room temperature, about 0.5 monolayer (ML) (1 ML = 1.8 Angstrom) may be magnetically inactive due to spin wa ve excitations in ultrathin films and about 1.5-2 monolayers-due to in termixing resulting from roughness. Trapezoidal-like magnetization pro files in ultrathin Py layers 4-7 monolayers thick are discussed in ter ms of percolation of magnetic clusters within a rough interface. The F MR linewidth depends on the thickness of Py layer as d(Py)(-2).