The exchange-bias effect provides unidirectional anisotropy to ferromagnetic thin-films in GMR and TMR sensors. It is weak because it relies on an inherently compensated coupling across a ferromagnet/antiferromagnet interface. We replace the antiferromagnet with a TbFe-based perpendicular-anisotropy amorphous ferrimagnet, coupling to an adjacent ferromagnet with 13À5mJ=m 2 for temperatures within 7.9-280 K. A large exchange-bias between 1.1 and 0.7 T in that temperature range ensues. The temperature dependence of the bias is step-like, and thus different from that of antiferromagnet-based exchange-bias systems. It suggests using this material in exchange-biased temperature assisted magnetic writing. V

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Magnetic ͓Co/ Pd͔ N multilayers grown on assemblies of spherical polystyrene particles were used as a model system for studying the influence of magnetic coupling on the magnetization reversal by changing the size of the nanoparticles as well as the total thickness of the deposited magnetic film. The coercive field and the switching field distribution are found to be strongly dependent on the size of the nanocaps and on the total thickness of the magnetic layer, indicating a strong influence of the magnetic dipole-dipole interaction on the magnetization reversal of the entire array of nanocaps. Moreover, magnetic viscosity measurements allowed the estimation of the magnetic activation volume representing the effect of thermal activation on the switching process. It was found that the magnetic activation volume is substantially smaller compared to the volume of the nanocap and almost independent of the number of bilayers, and thus the total thickness of the nanocap, supporting an inhomogeneous magnetization reversal process.

We report on magnetic structuring of ColPd multilayer films with strong perpendicular magnetic anisotropy by single-pUlse direct laser interference lithography technique. Multibeam laser interference generates patterns of various types. The intense laser irradiation at interference maxima causes chemical intermixing. at ColPd interfaces, leading to local changes in magnetic properties such as the creation of pinning centers and the reduction in the strength of magnetic anisotropy. We use magnetic force microscopy and Kerr microscopy to study the magnetization reversal processes in the patterned samples and find that the structures show three distinctly different behaviors depending on the intensity of the laser used for irradiation.

Magnetic nanopatterning of perpendicular hard disc media with perpendicular anisotropy, but preserving disc surface planarity, is presented here. Reactive ion implantation is used to locally modify the chemical composition (hence the magnetization and magnetic anisotropy) of the Co/Pd multilayer in irradiated areas. The 1 Corresponding author 2 procedure involves low energy, chemically reactive ion irradiation through a resist mask. Among N, P and As ions, P are shown to be most adequate to obtain optimum bit density and topography flatness for industrial Co/Pd multilayer media. The effect of this ion contributes to isolate perpendicular bits by destroying both anisotropy and magnetic exchange in the irradiated areas. Low ion fluences are effective due to the stabilization of atomic displacements levels by the chemical effect of covalent impurities.Key words: hard drive, perpendicular magnetic recording, CoPd multilayers, multilayer media, nanoimprint lithography. I.-IntroductionData storage is dominated by disc based magnetic recording technology that combines high capacity, reasonable read/write speeds and cost-effectiveness. The storage density has increased spectacularly through the last years as the ability to reduce magnetic bit volumes has improved. However, as the volume is reduced the magnetic anisotropy energy becomes compatible with the thermal energy k B T (superparamagnetic limit) and the magnetic information of the bits gets lost. New technologies and strategies are needed to postpone or circumvent this limit, , high anisotropy chemically synthesized nanoparticles media 7,8 ,to name a few. A review on fabrication challenges for patterned recording media has been published recently. 9Patterned perpendicular magnetic media is a combination of methods being investigated to further extend areal bit densities. 4,10,11 In this approach, the data are recorded and stored in an array of single-domain magnetic bits ("nanomagnets") that The use of ion irradiation through a mask to modify the magnetic properties of films is also of current interest. In particular, this last case has been studied in detail by Chappert et al. 25; Ferre et al. . These ions were selected since they could be divided into two types: chemically inert with Co or Pd (N) and chemically active like (P, As), since they can form a covalent bond with cobalt from the alloy.The ion stopping masks were defined by e-beam lithography by use of a Leica EBPG 5000+ working at 100 keV. For this purpose, a negative resist (MAN 2403) was spun onto the samples, with an optimum thickness sufficient to stop each type of ion, so the underlying magnetic layer is protected during the irradiation process except in those areas where the resist was removed. Prior to this step some gold marks were deposited on the sample to define arrays in order to locate the nanostructured areas for measurements purposes. After implantation, the resist mask was removed by oxygen plasma cleaner.Structural modifications were studied by X-ray diffraction (XRD) using a P...

While the process of metal induced crystallization (MIC) is widely used in the fabrication of thin film electronic devices, its application to the field of thermoelectrics is fairly new. Especially its implementation in the field of the classic thermoelectric material SiGe could lead to a low cost approach by combining the benefits of low thermal budget, self-doping, and thin film and sputter deposition compatibility. In this work, samples consisting of SiGe/Al multilayers deposited on aluminum oxide based substrates have been prepared. Special emphasis was put on the ratio of Al to SiGe and the resulting changes in transport properties during annealing. On the one hand a certain amount of Al is needed to ensure a complete MIC process for the SiGe, but on the other hand an excess of Al results in a metallic system with low thermoelectric efficiency. In-situ characterization during annealing of the samples was carried out via x-ray diffraction, electrical resistivity, and Seebeck measurements.

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Note: This paper is part of the Special Topic Collection on 30 years of the Nellie Yeoh Whetten Award -Celebrating the Women of the AVS.