Effects of layer thickness on orientation distribution and magnetic properties of CoCrTa/Cr films (original) (raw)
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Effects of substrate bias on crystal structures and magnetic properties of CoCrTa/Cr thin films
Materials Chemistry and Physics, 1996
Effects of negative d.c. substrate bias on the film properlies of CoCrTa/Cr magnetic recording media have been investigated. When the substrate bias was increased from zero to-250 V, the Ta content was found to increase from 3.9 to 15.0 at.%, whereas the Cr content decreased and the deposition rate was reduced. X-ray diffraction (XRD) analysis revealed the replicate growth of Co (1120) on the Cr (002) plane. The peak shift and line broadening of Co (1120) diffraction are attributed to the compositional change and presence of residual stress in the deposited film. The occurrence of maximum coercivity at-150 V bias is correlated to the formation of structural defects. However, too high a bias (-250 V) induces formation of an excessive amount of weak magnetic phase, which causes the magnetic properties to deteriorate. The enhancement of the cocrcivity due to substrate bias is primarily governed by hindrance of domain wall motion by structure defects and/or residual stress.
Journal of Materials Science, 1992
Bi-layer CoCrTa/Cr films were deposited on textured aluminium or textured NiP-plated aluminium substrate by d.c. magnetron sputtering. The crystal anisotropy and thereby magnetic properties depending on substrate material, substrate temperature and texturing, were investigated. The magnetic crystal anisotropy induced by the mechanical texture on aluminium or NiP/AI substrates along the texture lines for the film deposited at high temperature, were clearly observed, while the film deposited at Iow temperature shows less prominent anisotropic behaviour. X-ray diffraction analysis indicates a change in the preferred orientation of the chromium and CoCrTa films sputtered on different substrates at different temperatures. It was found that a high substrate temperature was beneficial to the formation of Cr(002) and therefore epitaxial growth of Co(1 1 7_0) on Cr(002) for either aluminium or N iP/AI substrates.
Magnetic and structural properties of Co/Cr multilayers with in‐plane anisotropy
Journal of Applied Physics, 1991
Previously we studied the effect of Cr spacer layer on in-plane coercivity in Co/Cr multilayered films. It was found that the high coercivity is related to the easy axis in-plane orientation and the character of the composition modulation. In this paper, the dependence of the saturation magnetization as a function of Co layer thickness is used to study the interface structure. The layer structure is confirmed by small angle x-ray diffractometry for typical films. The magnetic interaction among the grains is studied by examining deviation from the behavior predicted by the Wohlfarth model for noninteracting single-domain particles.
The magnetic and microstructural properties of Co-Cr thin films with perpendicular anisotropy
Journal of Magnetism and Magnetic Materials, 1983
This paper reports measurements of the magnetic properties of dc sputter deposited Col00_xCr x alloy thin films for 0 < x ¢ 30 ate. Properties of interest are those obtained from the in-plane and perpendicular hysteresis loops such as magnetization, saturation fields and coercivities. These properties are correlated with the microstructure, crystal structure and, to some extent, the magnetic domain structure of the films. For particular preparation conditions and within a certain composition range the films are found to have some of the properties suitable for perpendicular magnetic recording appfications, i.e., perpendicular magnetization and high coercivity.
Magnetic Anisotropy of Suppttered Co-Cr Thin Films
IEEE Translation Journal on Magnetics in Japan, 1989
Co-Cr and Co-Cr-W films were prepared by DC magnetron sputtering on PET film. The dependence of the magnetic anisotropy constants Kui and Ku 2 on the film thickness was determined from torque curve measurements. When the film thickness is thin, the Kui is very small, and it increases rapidly as the film thickness increases. On the other hand, the Ku 2 is extremely large for thin films, but drops rapidly with increasing film thickness, approaching a nearly constant value. The ratio Kui/Ku2 is not constant. The dependences of 2and04,thetiltanglesoftheeasymagnetizationaxisfromthefilmnormalforKuiandKu2,onthefilmthicknessweremeasured.Thevalueof2 and 04, the tilt angles of the easy magnetization axis from the film normal for Kui and Ku 2 , on the film thickness were measured. The value of 2and04,thetiltanglesoftheeasymagnetizationaxisfromthefilmnormalforKuiandKu2,onthefilmthicknessweremeasured.Thevalueof2 was not equal to that of 04. These results suggest that there is another fourfold symmetry besides that of the uniaxial anisotropy.
Compositional separation in CoCrTa perpendicular magnetic thin films
Journal of Magnetism and Magnetic Materials, 1996
Compositional separations in CoCrTa perpendicular magnetic thin films deposited at different substrate temperatures are observed using a transmission electron microscope equipped with an imaging filter. Quantitative elemental maps of cobalt and chromium are constructed for specimens deposited at substrate temperatures of 25, 170 and 230°C. Both intragrain and intergrain chromium segregation are observed at elevated substrate temperatures. High coercive force is obtained for specimens with extensive chromium segregation at the grain boundaries.
Structural and magnetic studies of Co thin films
Micron, 2006
The trend in reducing device dimension induces new physical properties and requires the development of measurement tools at the nanometer scale. This paper deals with the relation between magnetism and structure of thin films. We have chosen cobalt as a ferromagnetic layer and chromium as a bcc buffer. Magnetic and structural investigations have been led on epitaxial Co/Cr layers grown on MgO substrates. The thickness of the cobalt layer varies from 0.75 to 20 nm. Investigations on the cobalt layer by EXAFS and HRTEM give evidence for a bcc or a hcp structure depending on the cobalt thickness. Magnetic measurements using SQUID indicate that the saturation magnetisation per volume unit is constant for the layers. EELS experiments have been carried out to measure any evolution in the I(L 3 )/I(L 2 ) ratio for ferromagnetic layers of different thickness. We discuss the influence of structural and magnetic contributions on the evolution of the ratio with the cobalt thickness.
Correlation of Co[110]/Cr[002] texture and magnetic properties in CoCrTaPt granular films
IEEE Transactions on Magnetics, 1999
Studies of the effects of substrate temperature T, on the evolution of CO(1 10)/Cr(002) texture, magnetic and physical grain size, intergrain-interaction, anisotropy, orientation ratio of remanence and coercivity were investigated experimentally. It is found that the hcp-Co(l10)hcc-Cr(002) texture is improved with increasing T, from 27OC to 265°C. The intergrain-interaction, magnetic and physical grain size decrease with increasing Ts and reach their minima at T,-265°C where the magnetic grain size is close to the physical grain size. The correlation between the film microstructure and magnetic properties is studied systematically. Index tems-Co(1 lO)/Cr(OO2) texture, magnetic grain, intergraininteraction, x-ray rocking curve.
Effect of Ta buffer layer and thickness on the structural and magnetic properties of Co thin films
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2009
Single Co and Ta/Co bilayers were grown on Si͑100͒ substrates in a magnetron sputtering system. The effect of Ta buffer layer and the thickness of Co layer on the structural and magnetic properties of the Co layers has been studied. A single Co layer shows a textured structure above thickness of 40 nm according to the x-ray diffraction ͑XRD͒ pattern. The magnetic properties of Co layers depend significantly on the thickness of the films. Ta grows as highly textured -Ta ͑tetragonal͒ phase on Si with a smooth surface. The XRD and atomic force microscopy results show that the Ta buffer layer improves the structural properties dramatically, resulting in a strongly textured and smoother surface morphology. The Ta layer also affects the magnetic properties of Co layers to a large extent, especially inducing an in-plane anisotropy in thin Co films.