MAGNETIC-PROPERTIES AND DOMAIN-STRUCTURE STUDIES IN DC TRIODE-SPUTTERED PERMALLOY CARBON MULTILAYER FILMS

Double-layer and multiple-layer thin films of permalloy with carbon as a intermediate nonmagnetic spacer were prepared by low-energy dc triode sputtering. Coupling between the two layers of the double films is investigated on a series of samples with a fixed thickness of permalloy layers (d(p) = 300 angstrom) and thickness of the carbon layer d(c), varying from 0 to 25 angstrom. Thickness d(c) = 10 angstrom is found to be the limiting value for the carbon layer to be continuous and 20 angstrom for domain structures in the two magnetic films to decouple. Saturation magnetization M(s), uniaxial anisotropy field, H(k), and coercive force H(c) of multilayers with d(c) = 10 angstrom and d(p) from 50 to 600 angstrom (number of magnetic layers from 12 down to 1) are measured and found consistent with earlier results by other authors. Multiple domain walls in the multilayers are investigated by Lorentz electron microscopy.