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Studies of Longitudinally Oriented CoCrPt Thin Films for GMR Read Head

Author: LiSongTian
Tutor: WeiFuLin
School: Lanzhou University
Course: Condensed Matter Physics
Keywords: Intermediate layer Lanzhou University Magnetic layer Epitaxial growth Coercivity Texture Read head Magnetic recording media Easy axis of magnetization Thin film growth
CLC: O484
Type: Master's thesis
Year: 2008
Downloads: 7
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Abstract

CoCr base alloy thin film can be used not only as a traditional horizontal magnetic recording medium, but can also, for providing a horizontal magnetic field in the spin valve read head bias layer. Either as a horizontal magnetic recording medium, or the bias layer in the read head, in order to fully utilize the crystal of the HCP structure CoCr base alloy thin film magnetic anisotropy energy shall be so HCP structure of the CoCr-based alloy thin film easy axis of magnetization c- The axis is parallel to the film surface. In this paper, to select a suitable underlying layer and the intermediate layer, prepared by magnetron sputtering easy magnetization axis parallel to the film surface CoCrPt alloy thin film and from crystallography the epitaxial relationship departure CoCrPt media orientation system research. The following results were obtained: 1. Elevated Cr layer sputtering temperature can make Cr texture from (110) to (200) relatively good Cr (200) orientation can be obtained, when the deposition temperature is 300 ℃. 2 deposited directly on the Cr (200) on the substrate surface of the CoCrPt film coercive force and perpendicular to the film surface the size of the coercive force is quite easy axis in-plane orientation of the texture should have a coercive force value, and did not reach , on the one hand because the Cr underlayer (200) texture is not ideal, but also a certain ingredient (110) texture there. The other reason is caused due to the addition of the Pt due CoCrPt magnetic layer Co lattice expansion, so that the Cr substrate and the mismatch of the CoCrPt magnetic layer increases, the destruction of the original epitaxial growth conditions. These two reasons resulting in the Cr (200) is deposited directly on the substrate of the CoCrPt film easy axis are randomly oriented. 3 Cr (200) texture can be enhanced by adding a small amount of W in the Cr layer. The W content of 15% can be obtained when the optimization of Cr (200) orientation. W Add the expanded lattice of Cr, play the role of a reduced misfit in the lining between the bottom and the CoCrPt magnetic layer. 4 the CoCrPt film deposited on CrW substrate, no growth we expect with the Cr (200) plane of the epitaxial relations CoCrPt (11 (?) 0) texture, but growth of a (10 (? ) 1) of the texture. CoCrPt (10 (?) 1) surface and CoCrPt (11 (?) 0) plane of the one surface of the 28 degree angle. CoCrPt / Cr films compared with the easy magnetization axis randomly oriented, CoCrPt / CrW film magnetic aspects improved, in-plane coercivity increases, and larger than the coercive force of the perpendicular to the film plane, but the plane MH loops the rectangle is not very satisfactory, due to the easy axis orientation and the membrane surface is there a certain angle. 5 introduces CoCr Interlayer CoCrPt / CoCr / CrW film growth plane magnetization of CoCrPt (11 (?) 0) texture. Precisely because the optimization of the CoCrPt film surface orientation, so that its in-plane magnetic also have greatly improved. The added layer CoCr intermediate layer, the coercive force of the perpendicular to the film surface direction is further reduced, the in-plane coercive force was increased from the original 2.2 KOe increased to now 3.0KOe. Plane hysteresis loop rectangularity from S ~ * = 086 becomes now S * = 0.91. CoCr intermediate introduction to achieve in-plane magnetization of the CoCrPt plays a crucial role. Although we get better Cr (200) texture add elements by W, but the CrW substrate or a small amount of Cr (110) texture exist. By calculation, we know of CoCrPt (10 (?)) / / CrW (110) surface between the misfit respectively 1.0% and 2.2%, and of CoCrPt (11 (?)) / / CrW (200) crystal plane The misfit between 8.3% and 2.0%, respectively. CoCrPt (10 (?) 1) / / CrW (110) the misfit between the crystal surface is much smaller than the CoCrPt (11 (?) 0) / / CrW (200) crystal face misfit. From the viewpoint of thin film growth of the energy needed, Co (10 (?)) / / CrW (110) crystal plane between the epitaxial growth than of CoCrPt (11 (?) 0) / / CrW (200) crystal plane between the epitaxial growth is much easier. Because of this reason, the presence of a small amount of Cr (110) texture makes the CoCrPt film deposited on the substrate of CrW grown (10 (?) 1) texture. 7.CoCr the introduction of the intermediate layer, the epitaxial relationship between the adjust underlayer and surface played a very crucial role. CoCr intermediate layer added destroy the underlying layer and the surface layer of the original epitaxial relationship, thereby hindering of CoCrPt (10 (?)) / / CrW (110) crystal plane between the epitaxial growth. CoCr intermediate layer of Co HCP structure, it provides a template of an HCP structure, the growth medium for the surface of the CoCrPt thereby inducing come forward magnetized (11 (?) 0) texture of the CoCrPt film.

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