Microstructure of Longitudinal Media

Lü, Bin; Laughlin, David E.

doi:10.1007/978-3-642-56657-8_2

Cited by 11 publications

(3 citation statements)

References 224 publications

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“…Body-centered cubic ͑bcc͒ Cr underlayers have been widely used in magnetic recording technology to control the grain size and grain size distribution in magnetic media prepared by sputtering, 10 and in addition provide a close epitaxial match to hcp Co alloys, promoting the growth of hcp films with the c axis in the plane of the film and inducing an in-plane anisotropy. Electroplated hard magnetic films with in-plane anisotropy would exhibit magnetic properties complementary to those with perpendicular anisotropy described in previous publications, and may provide materials suitable for particular MEMS applications.…”

mentioning

confidence: 99%

Morphology and Magnetic Properties of Co-rich Co-Pt Thin Films Electrodeposited on Cr Seed Layers

Pattanaik

Zangari

2006

J. Electrochem. Soc.

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Co-Pt ͑Pt ϳ 20 atom %͒ alloy films were electrochemically grown at constant current density on Cr seed layers in order to study the influence of the Cr surface on their morphology and magnetic properties. The Cr seed layer favors the growth of a hexagonal close-packed phase, as revealed by X-ray diffraction. Morphological investigation using a scanning electron microscope revealed the electrocrystallization of Co-Pt on Cr to be proceeding through the nucleation and growth of three-dimensional ͑3D͒ clusters with columns growing outward in all directions from isolated nucleation centers. The 3D growth is likely due to the presence of a thin oxide layer on the Cr seed. At lower current density, individual micrometer-sized clusters were formed with distinct hexagonally shaped faces. Increasing current density results in a finer grain microstructure. At early stages of growth and low current density, the clusters exhibit a faceted morphology similar to that of the substrate. Samples prepared at higher current density or with larger thickness show larger coercivities, reaching values as high as 3490 Oe ͑278 kA/m͒ and 2275 Oe ͑181 kA/m͒ in the perpendicular and parallel directions, respectively, for a 500-nm-thick film deposited at 50 mA/cm 2 .Co-rich Co-Pt alloy thin films with composition about 20-25 atom % Pt are known to exhibit high magnetic anisotropy ͑MA͒ and high coercivity in the as-deposited state. These magnetic properties are reportedly induced either by the coexistence of a face-centered cubic ͑fcc͒ and a hexagonal close-packed ͑hcp͒ phase, 1 a microstructure composed of small hcp grains with nonmagnetic matter precipitated at the grain boundaries, 2 or by the growth-induced formation of a partially ordered metastable phase. 3,4 These alloys exhibit much lower anisotropies and coercivity than those typical of equiatomic face-centered tetragonal ͑fct͒ Co-Pt or Fe-Pt alloys; they do not require the postdeposition annealing at temperatures above 600°C that is necessary to start recrystallization and achieve formation of the fct phase. As such, Co-rich Co-Pt alloys constitute an attractive class of materials, in particular for permanent magnet components in microelectromechanical systems ͑MEMS͒, 5-7 where post-deposition annealing at high temperature is generally unacceptable from a processing standpoint.In previous work by our group 8,9 we have demonstrated that the electrochemical deposition ͑ECD͒ of Co-Pt ͑Pt ϳ 20 atom %͒ onto specific underlayers, e.g., fcc Cu ͑111͒, results in heteroepitaxial growth and favors the formation of a hexagonal phase, yielding single-phase hcp films with their c axis perpendicular to the film plane and high perpendicular anisotropy. ECD is an important technique in MEMS fabrication, since ECD through lithographic masks is a unique method for the growth of high aspect ratio threedimensional structures, providing also an outstanding control of the morphology, microstructure, and magnetic properties of the resulting components. ECD from an electrolyte with suitable chemistry has al...

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confidence: 99%

Morphology and Magnetic Properties of Co-rich Co-Pt Thin Films Electrodeposited on Cr Seed Layers

Pattanaik

Zangari

2006

J. Electrochem. Soc.

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“…There are many candidates for sputtering materials for recording layer and underlayer of tape, resulting from a long history of sputtered hard disk media. Recently, the most experienced material is a Co-alloy because sufficient magnetic properties and small grain size can be obtained for tape media [1]. Although CoPtCr alloy media have given excellent playback performance for a hard disk media, most of the media have been made by dc magnetron sputtering.…”

Section: Introductionmentioning

confidence: 99%

Playback Performance of Facing Targets Sputtered Tape Media on Moving Tape Substrate with a High Speed

Matsunuma

Inoue²,

Doi³

et al. 2008

IEEE Trans. Magn.

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Playback performances and microstructures of facing targets sputtered (FTS) longitudinal recording tape media on moving tape substrates were investigated at a fast (100 cm/min) and a slow (5.8 cm/min) moving speed. CoPtCr-SiO 2 granular magnetic layers were deposited on Ru underlayer on moving 4.5 m thick Aramid films by a FTS system at room temperature. Coercivity over 300 kA/m and grain structures with average diameter of 8 nm were achieved on very thin plastic film. Moving speed does not affect microstructure grown by FTS. The magnetic grains are physically isolated by segregation of silicon and chromium to grain boundaries. This was observed by transmission electron microscopy (TEM) and spot energy-dispersive X-ray spectroscopy (EDS). Cross-sectional TEM images show that straight columnar magnetic grains were grown and unaffected by the moving direction of the substrate. In playback tests, it was shown that both samples had over 8 dB higher SNR than commercial particulate tape media of 0.5 Gb/in 2 areal density.

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“…The growth of each of seed/under layers is carefully tuned through sputtering gas pressure ( 6 mTorr) and substrate temperature, typically 200-300 • C, to ensure the greatest possible grain refinement and the best possible lattice matching so that the grain size distribution is kept as narrow as possible and crystallographic defects in the recording layer are minimised. A detailed review of the physical mechanisms and materials used to set the crystallography and microstructure of longitudinal media has been given by Liu and Laughlin (2001). Longitudinal media are typically quaternary alloys of CoCrPtB (Doerner et al, 2001).…”

Section: Hdd Mediamentioning

confidence: 99%

Magnetic Data Storage: Past Present and Future

Thomson

Abelmann

Groenland

Magnetic Nanostructures in Modern Technology

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The design of media, heads, positioning systems and data detection and coding techniques for various generations of magnetic recording systems are discussed. We will start with current systems, such as longitudinal hard disc and tape. Next we will discuss the near future, where perpendicular recording (thicker films, higher stray fields) will address the problem of thermal stability. In the third section we will give an outlook on future developments (patterned media, thermally assisted recording, self assembled arrays of nanoparticles and probe storage).

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Microstructure of Longitudinal Media

Cited by 11 publications

References 224 publications

Morphology and Magnetic Properties of Co-rich Co-Pt Thin Films Electrodeposited on Cr Seed Layers

Morphology and Magnetic Properties of Co-rich Co-Pt Thin Films Electrodeposited on Cr Seed Layers

Playback Performance of Facing Targets Sputtered Tape Media on Moving Tape Substrate with a High Speed

Magnetic Data Storage: Past Present and Future

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