Structural and magnetic properties of Ni/Cr multilayers

Abstract Ni/Cr multilayers have been grown on Si(100) by dc triode sputtering. Three different samples have been investigated where the only purposely variable parameter is the superperiod: Λ = 52, 35 and 27 A. The Ni:Cr ratio was kept constant equal to 1:1 and the total thickness is about 1200 A. The quality of the layering is shown by the low-angle X-ray diffraction spectra which exhibit both thickness fringes and Bragg peaks. At large angles, weak superlattice peaks appear around the 110 Cr /111 Ni diffraction peak. Pole figure measurements indicate a fiber texture: for Ni and for Cr. The average stress in the stackings has been evaluated via curvature measurements: the samples are in a high state of compressive stress, larger than 1 GPa. Systematic magnetization measurements have been performed with a vibrating sample magnetometer as a function of temperature with the applied field parallel or perpendicular to the sample plane. All the multilayers exhibit in-plane anisotropy. The magnitude of the saturation magnetization indicates an important Ni-Cr intermixing at the interfaces. The temperature behaviour of the magnetic moment indicates two-dimensional effects.