Search

We have demonstrated magnetic recording at an areal density of 5 Gb/[in.sup.2] using Dual Stripe Magnetoresistive heads (DSMR) on low noise and low-glide height quaternary CoCrTa-based alloy thin film disks. The data rate is 120 Mb/sec with a PR4 channel, and the on-track error rate achieved is around [10.sup.-9]. The demonstration was accomplished in two cases using two different types of heads. In the first case, it was done with a DSMR head having shield-shield spacing of 0.165 [[micro]meter] and 1 [[micro]meter] stripe height flying at 25 nm, resulting in a linear density of 321.7 KBPI, and a track density of 15.6 KTPI. The second case was performed with DSMR heads having shield-shield spacing of 0.18 [[micro]meter] and .8 [[micro]meter] stripe height flying at proximity height of 12 nm, achieving a 358.75 KBPI and 13.8 KTPI. This is the highest linear density published so far for either GMR or AMR heads. It is the direct Consequence of high signal/noise of DSMR heads and proximity recording over low noise, low-glide-height media. To explore the large dynamic range of DSMR heads, this study was also done with a variety of low noise disks with Mrt ranging broadly from 0.45 to 1.0 memu/[cm.sup.2] and coercivity of 3000 Oe. Index Terms - DSMR, Proximity recording, Low Noise disks, Stitched Write heads

The effect of added block copolymer on the phase separation and morphology evolution in a partially miscible blend of polystyrene and polybutadiene near the critical composition is studied by temperature jump light scattering (TJLS) and transmission electron microscopy (TEM). As block copolymer is added, the phase boundary is shifted to lower temperatures and the phase separation process is slowed dramatically. Since the quench depth greatly affects the rate of phase separation in any blend system, we have used equivalent quench depths by adjusting for the shift in the phase boundary as block copolymer is added. The morphology evolution of these ternary blends was studied by preparing TEM specimens at equivalent shallow quench depths (ΔT = 1.6 ° C) and allowing each blend mixture to coarsen for the time required to reach a specific constant size, or q-value, using the TJLS data on the kinetics of phase separation. The q-range selected was q [similar to] 0.003-0.005 [nm.sup.-1], which corresponds to a spacing of 1-2 [µmeter] in real space. The combination of light scattering and microscopy techniques more rigorously describes the compatibilization process in these complex ternary systems., INTRODUCTION Polymer blends or alloys are often used as engineering materials and much emphasis has been placed on extending blending technology to different mixtures of homopolymers (1, 2). Since many [...]

The small angle neutron scattering (SANS) technique has been used to study the interfacial structure development in poly(methyl methacrylate)/polycarbonate (PMMA/PC) blends through transesterification. We found: 1) Development of interfacial structure through transesterification at the phase separated domain interfaces are observed at T ≤ 200 ° C. At T ≥ 215 ° C, because of a higher transesterification rate, the melting of domains is observed together with very weak scattering by interfacial structure. 2) Interfacial thickness [t.sub.i] increases with time and reaches a plateau value of [t.sub.i] at 32.5 ± 2.4 Å and 29.6 ± 3.7 Å for 180 ° C and 200 ° C, respectively. 3) The intensity profiles at 190 ° C and long times show the formation of spherical domains similar to those reported by Rabeony et al. (1). These may be caused by the crosslinking effect of the transesterification reaction between PMMA and PC., INTRODUCTION In our previous paper (2), we reported a small angle neutron scattering (SANS) study on bis-phenol A polycarbonate (PC)/co-polyester (PET) polymer blends, in which both phase separation and transesterification [...]

Dual-stripe MR heads with linear density capability of 200 KBPI and track density capability of 11,000 TPI have been manufactured. The write head, with a 15 turn coil and a gap length of 0.3 [[micro]meter], is made of conventionally plated Permalloy for both the leading and trailing poles. The thickness and track width of the trailing pole are 3.5 and 2.1 [[micro]meter], respectively. The MR elements have a 1.4 [[micro]meter] track width, 1.1 [[micro]meter] stripe height and a 17.5 nm thickness. The shield-to-shield separation is 0.18 [[micro]meter]. The two MR elements are mutually biased and patterned-exchange domain stabilized. Recording tests were performed on a thin-film disk with a coercivity of about 3000 Oe and an [M.sub.r]t of 0.75 memu/[cm.sup.2]. The read-back amplitude is as large as 1.02 mV (p-p), and the 50% roll-off density is as high as 160 kfci. Error rate test with a PRML channel at a data rate of 105 Mbits/s showed that a low on track error rate of [10.sup.-10] and an off-track capability of more than 15% of the track pitch could be easily achieved at a linear density of 200 KBPI and a track density of 11,000 TPI.

The shear response of a model polymer–clay gel is measured using small-angle neutron and light scattering, optical microscopy, and rheometry. As the flow disrupts the transient network that forms between clay and polymer, coupling between composition and stress leads to the formation of a macroscopic domain pattern, while the clay platelets orient with their surface normal parallel to the direction of vorticity. We discuss similarities with shear-induced structural transitions observed in other complex fluids, and we offer a physical explanation for the orientation of the clay platelets. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Three high-purity TiO2 (anatase) powders (TPF6, TBF4, and Tconventional) were prepared by the sol–gel method with/without ionic liquid as template and calcinations at 450°C. These powders were, then, characterized to investigate their differences in morphological properties. Electrochemical performances of the H2/O2 PEMFCs employing the Nafion composite membranes with these three TiO2 powders as fillers were studied over 80–120°C under 50% and 95% relative humidity (RH). The result showed that the order of the fillers effect on the performance at 80 and 90°C was the same as that of the TiO2 filler''s specific surface area (i.e. TPF6 >Tconventional >TBF4 >P25, a commercially available nonporous TiO2 powder). However, the order between Tconventional and TBF4 was reversed at 110 and 120°C under 50% RH. This indicates that the size and the amount of mesopores, which better confined the water molecules, were significant contributing factors to the performances at the higher temperatures. The best power density obtained under 50% RH at 120°C and a voltage of 0.4V was from the PEMFC with the TPF6-containing Nafion composite membrane. It was about 5.7 times higher than the value obtained from that with the recast Nafion membrane. [Copyright &y& Elsevier]

Non-linear analysis of a gyrotron using an axially grooved rectangular waveguide operating at the high harmonic I of the cyclotron frequency Ω[sub c] is given. We use 120 electrons in the simulation of the electron beam. The growth rate, electric field, relativistic factor γ and phase factor are calculated as functions of the slip parameter χ = lΩ[sub o]/ωγ[sub o] for the chosen optimized operating parameters of the gyrotron. Efficiency of ∼20% in the electron-beam frame is possible for the sixth harmonic of the cylotron frequency which increases to 58% in the second harmonic. [ABSTRACT FROM AUTHOR]

Studies the development of a thermally stable, nonspiking ohmic contact to p-GaAs based on the solid-phase regrowth mechanism. Contact resistivity as a function of annealing temperature; Planar interface between the metallization and the GaAs substrate after annealing; Proposed reaction that leads to the formation of the ohmic contact.

Discusses the use of the principle of solid phase regrowth (SPR) to induce compositional disordering in superlattice structures compared to the conventional diffusion method. Requirement of SPR of thin film deposition and annealing; Improvement of the crystal quality and the photoluminescence signals emerging from the disordered region with increasing processing temperature.