Cock Lodder

Oblique evaporation and surface diffusion

The special structure of obliquely evaporated films has its origin in shadowing phenomena during film growth. Because of shadowing, the film consists of bundles of inclined columns with the bundles being aligned perpendicularly to the vapour incidence direction. The column inclination angle lies between the film normal and the vapour incidence direction. Different models found in literature relating process parameters and film structure are discussed. It is found that surface diffusion plays an important role, especially with regard to the difference between random and directional surface diffusion. The latter is induced by the oblique evaporation process. A quantitative expression is given for the relation between process conditions and surface diffusion including the influence of substrate temperature, rate and contamination with residual gasses. Using these models and adding our new calculations, the relation between surface diffusion and film structure is discussed in detail and found to be consistent with measurements published in the literature.

Magnetic force microscopy of thin film media for high density magnetic recording

This paper discusses various aspect of magnetic force microscopy (MFM) for use in the field of high density magnetic recording. After an introduction of the most important magnetic imaging techniques, an overview is given of the operation and theory of MFM. The developments in instrumentation, MFM tips, quantification of MFM data, high resolution imaging and application of external fields is discussed. Examples are given of the applications of MFM, such as the characterization of heads, magnetic structures (bits) in longitudinal and perpendicular recording media, bits in magneto-optic films and domain structures in soft magnetic materials.

Tailoring growth and local composition by oblique-incidence deposition: a review and new experimental data

In this paper features are discussed that are related to the nucleation and growth of thin films deposited by physical vapour deposition. Although the paper is mainly focused on oblique-incidence deposition, a normally-impinging vapour flux will also be described. Two cases of oblique-incidence deposition will be discussed: one obliquely-impinging flux and two obliquely-impinging fluxes from opposite directions. With respect to the microstructure, both similarities and differences between these deposition will be described. Further, a special feature of two obliquely-impinging vapour fluxes is dealt with, which is the local composition in the lateral direction (parallel to the substrate). The oblique and opposing directions can induce an inhomogeneous chemical composition. This process is referred to as process-induced compositional separation. In addition to reviewing the literature, the paper summarizes experimental data on obliquely co-evaporated Co-Cr, Co-Ag and Co-Ta films. It will be shown from these experimental data that the two vapour directions can be exploited to tailor compositional inhomogeneities.

Comparing the resolution of magnetic force microscopes using the CAMST reference samples

A set of reference samples for comparing the results obtained with different magnetic force microscopes (MFM) has been prepared. These samples consist of CoNi/Pt magneto-optic multilayers with di¤erent thicknesses. The magnetic properties of the multilayer are tailored in such a way that a very Þne stripe domain structure occurs in remanence. On top of this intrinsic domain structure, bits were written thermomagnetically using di¤erent laser powers. These samples have been imaged in six di¤erent laboratories employing both home-built and commercial magnetic force microscopes. The resolution obtained with these different microscopes, tips and measurement methods varies between 30 and 100 nm.

Micromagnetic simulation of a flux guide for a read head with sub-100 nm resolution

Large scale 3D micromagnetic simulations are performed on single pole read heads with pole tip cross sections of 45345 and 1003200 nm. It is shown that tips with these dimensions have a much higher output than predicted by an analytical theory using the reciprocity theorem. The larger of these tips still behaves in a relatively soft manner and has an output waveform shape very close to the one predicted by the analytical model. The response of the small tip however is hysteretic.

The CantiClever. A dedicated probe for magnetic force microscopy

Summary form only given. With the current rate of increase in areal density of magnetic recording systems, todays resolution of MFM needs to be improved in order to remain useful as a measurement tool. The resolution of MFM is amongst others determined by the geometry of the magnetic tip, which for commercial probes consists of a thin magnetic coating deposited on a pyramidal Si AFM tip. Analysis of the imaging process shows that the shape of these tips is not ideal. For higher resolution, the tip must be shaped as an elongated bar with a flat front end. In this contribution we present a completely new MFM cantilever, the CantiClever, which is not derived from traditional AFM probes but optimized for MFM. Our design incorporates the cantilever and the magnetic tip in a single manufacturing process with the use of silicon micromachining techniques, allowing for batch fabrication of the probes. We realise the ideal tip shape by deposition of the magnetic material (Co) on the side of a free hanging silicon nitride layer.

The influence of Tantalum content in relation to substrate temperature on magnetic and structural properties of Co-Cr-Ta thin films

In this study, we investigated the influence of Ta content (in Co86Cr12Ta2 and Co82Cr13Ta5 compositions) on magnetic and structural properties of Co–Cr–Ta perpendicular media samples grown on Si substrates at different substrate temperatures during RF-sputter deposition. In general, coercivity of Co82Cr13Ta5 samples is higher than that of Co86Cr12Ta2 samples, whereas the perpendicular c-axis orientation of Co86Cr12Ta2 samples is better. Ta content was suggested to be in between 2 and 5 at% to give optimum magnetic and structural properties.

Morphology and Texture of Co-evaporated Co-Cr Films

The microstructure of co-evaporated Co-Cr films is investigated. The columnar morphology is tilted towards the main source. Due to the geometry effect of opposing vapour directions, compositional separation occurs. With AES direct proof of this was established. Consequently it is unnecessary to increase the substrate temperature to obtain enhanced energy products.

The influence of demagnetization on the magnetic after-effect of Co-Cr micro structures

The influence of the demagnetization field on the magnetic after-effect of Co-Cr media is discussed. The demagnetizing field of as-sputtered Co-Cr was changed into block-shaped micro structures by lithographic processes. This process does affect the shearing of the perpendicular hysteresis curve but not the intrinsic magnetic properties. A linear relation was obtained between the coefficient of magnetic viscosity and the slope of the hysteresis curve. >

Magnetic Force Microscopy - Towards higher resolution

In this chapter Magnetic Force Microscopy is treated in detail. The emphasis is on high resolution and the design and realisation of MFM tips.