Ni/Pt multilayers: growth and magneto‐optics

Abstract

PACS 68.65. Ac, 78.20.Ls Ni/Pt multilayers were grown on glass, Si and polyimide substrates by e-beam evaporation under ultrahigh vacuum conditions. The deposition temperature was maintained just above room temperature, T dep ∼ 40 o C. X-ray diffraction experiments showed that the samples have almost as high quality as similar ones grown at higher temperatures. Atomic Force Microscopy images revealed small nanocrystallites with diameters in the range of 15-30 nm. The film roughness and the size distribution of the crystallites were found to be substrate-dependent. It is shown, however, that differences in the morphology among samples with the same Ni and Pt thickness grown on different substrates do not affect the magnetic and magnetooptic properties. The magneto-optic response is discussed with respect to the spin-polarization of Pt at interface proximity with Ni, recently observed in Ni/Pt multilayers. 1 Introduction Magnetic multilayers of the type 3d/Pt (3d = Fe, Co, Ni) are promising materials for perpendicular magneto-optic recording. Appealing features for such applications include the perpendicular magnetic anisotropy and the large Kerr rotation at the high energy range of the spectra (∼ 3-4 eV) [1,2]. The microscopic origin of both properties has been related to modifications of the magnetic properties of the 3d element resulting from the induced spin-polarization of Pt and hybridization of the electronic structure at the interfaces of the multilayers [3][4][5]. However, frequently, deposition and filmgrowth parameters may modify magnetic and magneto-optic features of samples in a way that is not always straightforward [1]. Ni/Pt multilayers present sharp interfaces with negligible amount of interdiffusion [6][7][8]. Thus, in this work we have selected Ni/Pt multilayers as a prototype system to compare the correlation between growth and magneto-optics on samples with identical individual layer thickness, prepared, however, on different substrates. We demonstrate that the substrate selection may modify the film morphology and, to a less extent, the layer quality, while, the magnetic and magneto-optic response remain practically unaltered.