The coercivity mechanism of (Co/Pt) multilayers with high H/sub c/ and high squareness fabricated by sputtering is mainly due to the wall pinning rather than the nucleation process. In order to estimate the size of a wall-pinning site, a study of the temperature dependence of the coercivity, perpendicular magnetic anisotropy, and saturation magnetization for multilayers fabricated under various substrate conditions has been carried out. The size r/sub 0/ of the pinning sites of about 4 AA was obtained for the multilayer film deposited onto an etched SiN/sub x/ film. The size r/sub 0/ increases with less interface-sharpness, which was confirmed by X-ray low angle diffraction. This implies that the pinning site is closely related to the interfacial region. An inhomogeneity near the interface between Co and Pt is believed to play a major role as pinning for a wall motion. This result is compared to the case of Tb/sub 26/(FeCo)/sub 74/ films, where the size is found to be about 60 AA approximately 250 AA. >

Coercivity mechanism and microstructure of (Co/Pt) multilayers

Perpendicular exchange bias has been observed for IrMn∕[Co∕Pt]n and [Pt∕Co]n∕IrMn multilayers in the as-deposited state. The exchange bias field is largest when the IrMn film is grown on magnetically saturated Co∕Pt multilayers (8.12mT for n=3), whereas it is considerably smaller when domain formation in the IrMn film occurs before Co∕Pt deposition (3.30mT for n=3). After annealing at 220°C in an out-of-plane magnetic field the perpendicular exchange bias field and magnetic anisotropy are considerably larger for the Co∕Pt multilayers with an IrMn film at the bottom. The apparent correlation between bias and anisotropy is explained by the dependence of the perpendicular exchange bias field on the orientation of the Co spins near the Co∕IrMn interface.

/pdf/correlation-between-perpendicular-exchange-bias-and-magnetic-rfwa1lfrdc.pdf

Correlation between perpendicular exchange bias and magnetic anisotropy in IrMn∕[Co∕Pt]n and [Pt∕Co]n∕IrMn multilayers

The domain structure of sputtered Co‐Pd multilayer films of varying thickness has been investigated by magnetic force microscopy. The domains appear as stripe domains, typical of perpendicularly oriented films. The size of the domains was strongly influenced by the thickness of the film. The domain repetition lengths give an additional experimental parameter which has been used to provide a stronger test of a theoretical model developed for ferromagnetic multilayer films [H. J. G. Draaisma and W. J. M. de Jonge, J. Appl. Phys. 62, 3318 (1987)]. It is found that the experiment and theory are broadly in agreement provided that the increased magnetization of the multilayer caused by polarization of the Pd is accounted for. There is a noticeable difference between the variation of the measured and theoretical domain repetition lengths with film thickness. This is attributed to the effects of domain‐wall pinning which is not considered in the model. It is estimated that the characteristic length of the films i...

Magnetic force microscopy of Co-Pd multilayers with perpendicular anisotropy

The pinning of flux lines by two different types of regular arrays of submicron magnetic dots is studied in superconducting Pb films; rectangular Co dots with in-plane magnetization are used as pinning centers to investigate the influence of the magnetic stray field of the dots on the pinning phenomena, whereas multilayered Co/Pt dots with out-of-plane magnetization are used to study the magnetic interaction between the flux lines and the magnetic moment of the dots. For both types of pinning arrays, matching anomalies are observed in the magnetization curves versus perpendicular applied field at integer and rational multiples of the first matching field, which correspond to stable flux configurations in the artificially created pinning potential. By varying the magnetic domain structure of the Co dots with in-plane magnetization, a clear influence of the stray field of the dots on the pinning efficiency is found. For the Co/Pt dots with out-of-plane magnetization, a pronounced field asymmetry is observed in the magnetization curves when the dots are magnetized in a perpendicular field prior to the measurement. This asymmetry can be attributed to the interaction of the out-of-plane magnetic moment of the Co/Pt dots with the local field of the flux lines and indicates that flux pinning is stronger when the magnetic moment of the dot and the field of the flux line have the same polarity.

https://fys.kuleuven.be/vsm/nsm/pubdoc/phc12-19mvb.pdf

Flux pinning by regular arrays of ferromagnetic dots

Influence of saccharin on the structure and corrosion resistance of electrodeposited Cu/Ni multilayers

The magnetic properties of thin film Pt/Co multilayers with perpendicular magnetic anisotropy depend on their preparation. Vapor‐deposited and Xe‐sputtered multilayers have the largest anisotropy energy and coercivities, attractive for magneto‐optical recording media. Films sputtered with a smaller mass gas (Ar) have less attractive magnetic properties. In this paper it is shown by high resolution electron microscopy that microstructural differences, related to the energetics of the deposition process, caused the differences in magnetic properties. Films prepared by Ar‐sputtering experienced energetic bombardment by reflected Ar neutrals and consequently had smooth, continuous Co and Pt layers, but only modest (111) fcc texture. Vapor‐deposited and Xe‐sputtered films, which experienced much less energetic bombardment, had superior (111) texture and sharp column boundaries, although Co–Pt layer interfaces were rougher. It was concluded that the superior (111) fcc texture was responsible for a large magneti...

Z. G. Li

Papers

Microstructural dependence of magnetic properties of Pt/Co multilayer thin films