Eur. Phys. J. B 7, 347-357 (1999)
https://doi.org/10.1007/s100510050621

Structural origin of magnetic anisotropy in Co-Pt alloy films probed by polarized XAFS

¹ INFN, Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati Roma, Italy
² INFM -GILDA CRG c/o ESRF, B.P. 220, 38043 Grenoble, France
³ Institut de Physique et Chimie des Matériaux de Strasbourg, GEMM (UMR 46 CNRS-ULP) , 23 rue du Loess, 67037 Strasbourg Cedex, France
⁴ Laboratoire de Cristallographie, CNRS, B.P. 166, 38042 Grenoble, France
⁵ Laboratoire de Physique des Liquides et Électrochimie ( UPR 15 CNRS) , Université Pierre et Marie Curie, 75230 Paris Cedex 05, France

Received: 29 April 1998
Revised: 27 July 1998
Accepted: 31 August 1998
Published online: 15 February 1999

Abstract

Polarized X-ray absorption fine structure (XAFS) measurements at the Co K and Pt L₃ edges show that the perpendicular magnetic anisotropy found in epitaxial fcc CoPt₃ (111) films stems from the existence of anisotropic local ordering. Such ordering, induced during the codeposition process and dependent on the growth temperature, is characterized by preferential CoCo pairs in the film plane, balanced by preferential CoPt pairs out of the plane, resulting from some Co 2D-segregation. Polarized XAFS at the Pt edge reveals similar anisotropic local ordering in epitaxial hcp Co₃Pt (0001) films exhibiting a larger magnetocrystalline anisotropy compared to that of bulk hcp Co. Besides, a polarization dependence of the Co XANES profile is observed only for the Co₃Pt films exhibiting hcp symmetry.