Structural and spectroscopic magneto-optic studies of Pt–Ni multilayers

Abstract

Pt m – Ni n multilayers were grown by e-beam evaporation under ultrahigh vacuum; m and n will depict the number of atomic planes of the corresponding constituents in one modulation period and, in this work, they were varied between 1 and 14. X-ray diffraction and conventional electron microscopy experiments revealed a fcc polycrystalline structure with excellent modulation. Magneto-optic properties, studied at room temperature between 1.5 and 5.2 eV, were found to depend strongly on both m and n. Perpendicular anisotropy was exhibited for samples with thin Ni layers and, unexpectedly, for thicker Ni layers when Pt layers became considerably thin (m∼2). Comparison of the magneto-optic features of two similar samples grown on glass and polyimide revealed that the choice between glass and polyimide does not affect magneto-optic properties.

Ni/Pt multilayers: growth and magneto‐optics

“…The grain size varies between 15-30 nm. The samples are more homogeneous in terms of grain-size distribution when compared to similar multilayers grown, however, at higher temperatures [6] which consist of crystallites of about 30-250 nm in diameter. The narrowest grain-size distribution is exhibited by the sample grown on glass, as Fig.…”

“…The Pt diffraction peaks are due to the 17 nm thick Pt buffer layer and the 5 nm thick Pt overlayer. The presence of satellite diffractions up to the second order in the high-angle XRD spectrum indicates the good quality of layering [6]. From the positions of the solid solution diffraction (denoted by '0') and the satellites we find that each multilayer period consists of 5 atomic layers of Pt and 5 atomic layers of Ni [6], that is we have a Ni 5 /Pt 5 multilayer.…”

“…Following the analysis described in [6] we find a quality ratio Q ∼ 65-70% for these samples. This value has to be compared with Q ∼ 70-80% for samples with similar individual layer thickness, but grown at higher temperatures in the range of 100-200 o C [6,10]. Therefore, a first conclusion to be drawn is that the multilayer quality is only slightly reduced by decreasing T dep .…”

“…2 one may see AFM images from the three Ni 5 /Pt 5 multilayers grown on (a) glass, (b) Si and (c) Kapton. The small grains are actually the top view of columns, since such samples present a columnar morphology [6]. The grain size varies between 15-30 nm.…”

“…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.…”