X-RAY-DIFFRACTION MEASUREMENTS OF LATTICE STRAINS IN CO PD(001) SUPERLATTICE FILMS/

Lattice spacings in fcc-Co/Pd(001) superlattice films grown on GaAs(00 1) substrates with a Ag(001) buffer layer were measured using a four-c ircle diffractometer. For samples with Co layers thinner than 9 angstr om and Pd layers thinner than 12 angstrom, the observed in-plane (110) lattice spacings were all 2.71 +/- 0.01 angstrom, indicating 8.0% lat tice expansion of Co layers and 1.5% lattice contraction of Pd layers. The (002) lattice spacings along the growth direction were estimated from a profile fitting method, and they were 1.60 +/- 0.02 angstrom fo r Co layers and 1.98 +/- 0.02 angstrom for Pd layers. This means that Co layers are contracted nearly 10%, while Pd layers are expanded 2% a long the growth direction of the superlattice films. The estimated lar ge lattice strains are successfully applied to explain the large magne tovolume contribution to the magnetic anisotropy reported previously.