In-plane C-axis Research Articles

The effect of Cr and W nucleation layers on the magnetic properties of CoPt films

CoPt and CoCr alloy films have received considerable interest recently for use as recording media in high-density recording technology. Chromium films have been used as nucleation layers to improve the magnetic properties of hcp magnetic alloy films (CoNi, CoNiCr, and CoCr) by increasing the in-plane c-axis preferred orientation. In this investigation, Co80Pt20 magnetic films were deposited onto 1000-Å-thick nucleation layers of chromium, a chromium-vanadium alloy or tungsten. Deposition of Co80Pt20 films onto W produced a significant increase in coercivity compared to the Cr nucleation layers. Coercivity values as high 2400 Oe were observed for the W/Co80Pt20 composite structure compared to about 1900 Oe for the CrV/Co80Pt20 structure.

Effect of Substrate Inclination on c-Axis Orientation and In-Plane Squareness Ratio in RF-Sputtered Co–Cr Films

Effect of Substrate Inclination on c-Axis Orientation and In-Plane Squareness Ratio in RF-Sputtered Co–Cr Films

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 V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RF</inf> , the argon pressure P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ar</inf> and the substrate holder temperature T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sh</inf> , 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 remanence <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S//= (M_{r}/M_{s})</tex> . Measurements of the substrate temperature T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf> as an function of the various sputter parameters lead to the conclusion that an exclusive perpendicular c-axis orientation is only obtained at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_{s} \sim 15\theta\deg</tex> c. At other T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf> established either directly by changing T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sh</inf> or indirectly by changing the sputter conditions an additional hcp compound with in-plane c-axis orientation appears. We concluded that T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf> is the dominant parameter for sputtering CoCr layers.

Studies of the morphology of one-way drawn poly(ethylene terephthalate) films by X-ray diffraction

Films made by stretching amorphous poly(ethylene terephthalate) (PET) in one direction have been examined using techniques of wide- and narrow-angle X-ray diffraction. The films were not subsequently annealed. The in-plane c-axis orientation of crystallites was assessed from measurements of reflections from 1̄05 crystal planes as in the method of Dumbleton and Bowles. However, we found that rather than tending to align parallel to the draw direction, the crystallites tended to lie in two groups inclined at a small angle to the draw direction. The angle of tilt of this ‘preferred’ direction to the draw axis became smaller for more highly drawn films, and a plot of tensile strength against tilt angle shows a trend to a ‘strength limit’ for zero tilt. (This tilt must not be confused with the well-known and quite different crystalline tilt which occurs after drawn PET is annealed.) Wide-angle diffraction has also been used to estimate crystal dimensions, and low-angle diffraction was used to determine long-period spacings. An analysis of the shape of the diffraction maxima gave an estimate of the shape of the diffracting units, and their influence on mechanical properties is discussed.

378. Vacuum in medicine: J. Bounden and J. Rotblat, Vacuum, 9, 1–16, 1959

The graphitic forms of carbon, boron nitride, and carbon nitride grown in energetic film-deposition processes or processed using ion irradiation often possess an in-plane c-axis texture. In this texture the basal planes of the graphitic material are perpendicular to the substrate. We show that the in-plane c-axis texture can be produced through plastic deformation as a mechanism to relieve the large ion-induced compressive stresses in these materials. Specifically, basal-plane slip and kinking processes would produce a rotation of the c-axis towards the plane of biaxial compressive stress. Once the c-axis has rotated to lie in the plane of the substrate, further deformation by basal-plane slip cannot occur. Then, in the absence of additional stress-reduction pathways, the stress level will rise if the material undergoes further compressive elastic strain. The possible relationship between this stress build-up and nucleation of high-density phases, such as cubic boron nitride, is briefly discussed.