Eur. Phys. J. B 22, 193-201 (2001)
https://doi.org/10.1007/s100510170127

X-ray absorption analysis of sputter-grown Co/Pt stackings before and after helium irradiation

¹ Institut d'Électronique Fondamentale, Université Paris-Sud, CNRS UMR 8622, 91405 Orsay Cedex, France
² Laboratoire Louis Néel, CNRS, BP 166, 38042 Grenoble Cedex 9, France
³ Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Université Paris-Sud, CNRS UPR 6412, 91405 Orsay Cedex, France
⁴ European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France

Corresponding author: ^a devolder@ief.u-psud.fr

Received: 10 April 2001
Published online: 15 July 2001

Abstract

We have studied the local order around cobalt atoms in Pt/Co/Pt layered systems gradually modified by irradiation using 30 keV helium ions. Using X-ray diffraction and X-ray Absorption Fine Structure, we have determined the crystallographic order, the number of Co-Co and Co-Pt bonds and the corresponding bond lengths both in-plane and in the perpendicular direction. The comparison with an interdiffusion model highlights the unexpected complexity of the initial Pt/Co/Pt nanostructure. We use the Néel/Bruno model of magnetic anisotropy to correlate the structure and the magnetic hysteresis properties. We then identify the structural consequences of irradiation onto the short range order. The irradiation induces a substitutional mixing maintaining the initial crystallographic structure. We confirm that the mixing rate is in agreement with a ballistic mechanism of mixing. In addition, we show that the previously reported irradiation-induced controlled decrease of the magnetic anisotropy can not be solely attributed to Co-Pt intermixing: irradiation also significantly releases the 3.4% tensile strain of the cobalt-rich dense planes. We finally speculate on the class of magnetic materials the concept of light ion irradiation could be extended to.