IN-SITU MAGNETIC AND STRUCTURAL-ANALYSIS OF EPITAXIAL NI80FE20 THIN-FILMS FOR SPIN-VALVE HETEROSTRUCTURES

We have investigated structural and magnetic properties of epitaxial ( 100) Ni80Fe20 films grown on relaxed Cu/Si(100) seed layers. The cryst allographic texture and orientation of these films was analyzed in sit u by reflection high energy electron diffraction (RHEED), and ex situ by x-ray diffraction and cross-sectional transmission electron microsc opy (XTEM). In particular, RHEED intensities were recorded during epit axial growth, and intensity profiles across Bragg rods were used to ca lculate the surface lattice constant, and hence the film strain. XTEM analysis indicated that the epitaxial films had atomically abrupt inte rfaces. The magnetic properties of these epitaxial films were measured in situ using magneto-optic Kerr effect magnetometry. Large H(c) (10- 20 Oe) was observed for epitaxial Ni80Fe20 (100) films less than 10.0 nm thick whereas for larger thicknesses, Hc decreased to a few Oe with the appearance of a uniaxial anisotropy. Correlations were made betwe en magnetic properties of these epitaxial films and the strain in the film.