Influence of R.F. sputter parameters on the magnetic orientation of Co-Cr layers

Co-Cr layers for the perpendicular recording mode were deposited by means of RF-sputtering. The most important sputter parameters, i.e. the RF sputter high voltage VRF, the argon pressure Parand the substrate holder temperature Tsh, gave an optimum value for perpendicular orientation of the magnetization. The crystal structure is always hcp within the ranges of varied parameters and no other magnetic phases were observed. If the sputter parameters do not have optimum values an additional hcp compound with in-plane orientation of the c-axis is observed. This orientation causes an increase of the in-plane remanenceS//= (M_{r}/M_{s}). Measurements of the substrate temperature Tsas an function of the various sputter parameters lead to the conclusion that an exclusive perpendicular c-axis orientation is only obtained atT_{s} sim 15thetadegc. At other Tsestablished either directly by changing Tshor indirectly by changing the sputter conditions an additional hcp compound with in-plane c-axis orientation appears. We concluded that Tsis the dominant parameter for sputtering CoCr layers

Characteristics of RF-sputtered CoCr films

The magnetization of the CoCr recording medium has been investigated by several methods. First the perpendicular hysteresis loops are analysed in the thickness range from 500 to 20,000 Å. This provided evidence that the magnetization process is typefied by domain wall motion. Second the dependence of the coercivity on the film thickness has been determined. The dependence found can be explained if it is assumed, that the coercivity is caused by domain walls, impeded by the crystallite boundaries. Finally stand-still recording experiments have been performed, which confirm that magnetization takes place by the displacement of domain walls. The switching criterion in the writing process is best met by taking the field averaged over the film thickness

Co-Cr films for perpendicular recording

Co-Cr films were prepared by means of RF-sputtering. The dependence of the magnetic parameters on the sputter conditions was investigated. It was found that for increasing Ar-pressure the c-axis of the hcp-structure gradually declines from normal to in-plane orientation. An optimum for the sputter voltage is found. The coercivity increases with decreasing target-substrate distance and this is probably due to surface heating by electron bombardment from the Ar-plasma. The recording characteristics of these Co-Cr films were then investigated by means of stand-still recording experiments. A 6.7 mm thick permalloy single-pole head (SPH) was used for creating a head print in a 1 mm thick Co-Cr layer. The flux reversals are detected by means of a magneto-resistive transducer (MRT). The response was analyzed, using a analytical method for calculating the magnetization distribution in the Co-Cr layer. For this purpose the head field of the SPH was also determined with the same MRT

CML: the commonKADS conceptual modelling language

We present a structured language for the specification of knowledge models according to the CommonKADS methodology. This language is called CML (Conceptual Modelling Language) and provides both a structured textual notation and a diagrammatic notation for expertise models. The use of our CML is illustrated by a variety of examples taken from the VT elevator design system

De werkvloer van een Kennisnetwerk Vitaal Platteland; Kennis maken met regionale kennisarrangementen

Op welke wijze kan het samen leren doen bij gebiedsontwikkeling worden ondersteund en wat kan een landelijk kennisnetwerk vitaal platteland daaraan toevoegen? Dit was het vertrekpunt voor een aantal werkbezoeken van de werkgroep kennisnetwerk vitaal platteland aan enkele regionale kennisarrangementen als onderdeel van een gezamenlijk leertraject. Dit verslag presenteert de bevindingen en komt met aanbevelingen voor een kennisnetwerk vitaal in wording. What support can be provided to joint learning in area development and what can a national knowledge network for a vital countryside add? This was the starting point for visits to various regional knowledge arrangements by the work group involved in the knowledge network for a vital countryside project as part of a joint learning programme. This report presents the findings and presents recommendations for a vital knowledge network for a vital countryside in the making