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1

Digitale Medien

Materials and processing aspects of CoCrTa/Cr longitudinal recording media. II. Microstructure (1994)

Shen, Y. ; Wong, B. Y. ; Laughlin, D. E.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 76 (1994), S. 8174-8179

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: In the CoCrTa/Cr system, it has been postulated that segregation of nonmagnetic constituents to grain boundaries is responsible for the low noise and high coercivity. However, direct experimental evidence is still lacking. In this investigation, we have carried out microstructural studies using transmission electron microscopy (TEM) and atomic resolution transmission electron microscopy (ARTEM) of CoCrTa/Cr films produced under varying processing conditions. We found that the stacking fault density and the degree of crystalline perfection between the faults is most important in increasing the coercivity and improving signal-noise properties as indicated by ΔM measurement. High substrate temperatures and high Cr and Ta concentrations promote the occurrence of the stacking faults in the films. In conjunction with ARTEM results, we propose that these faults provide possible sites for elemental segregation which is partially responsible for reducing the magnetic coupling among the unfaulted hcp regions in the CoCrTa films. We also provide microstructural evidence supporting the picture that the high-frequency mechanical texture lines break the intergranular coupling normal to the texture lines resulting in circumferential anisotropy. Grains are crystallographically correlated to form clusters between the texture lines but such correlation is broken up by the texture lines. This gives rise to an effective shape-induced anisotropy. We believe that the cluster size plays a more important role than does the grain size in determining the magnetic properties of CoCrTa/Cr media. © 1994 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.357869

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2

Digitale Medien

Stresses, curvatures, and shape changes arising from patterned lines on silicon wafers (1996)

Shen, Y.-L. ; Suresh, S. ; Blech, I. A.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 80 (1996), S. 1388-1398

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Experimental and numerical results are presented on the evolution of stresses and the accompanying changes in the overall curvatures due to the patterning of silicon oxide lines on silicon wafers and subsequent thermal loading. The finite element analysis involves a generalized plane strain formulation, which is capable of predicting the wafer curvatures in directions parallel and perpendicular to the lines, for both the patterning and thermal cycling operations. The predictions compare reasonably well with systematic curvature measurements for several different geometrical combinations of the thickness, width and spacing of the patterned lines. The non-uniform stress fields within the fine lines and the substrate are also analyzed. It is shown both experimentally and theoretically that certain geometries of patterned lines on the substrate induce dramatic shape changes and reversals of curvature in the direction perpendicular to the lines. The mechanistic origin of this effect is identified to be the Poisson effect arising from the anisotropic strain coupling in the patterned structure. © 1996 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.362938

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3

Digitale Medien

Materials and processing aspects of CoCrTa/Cr longitudinal recording media. I. Processing and magnetic properties (1994)

Shen, Y. ; Laughlin, D. E. ; Lambeth, D. N.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 76 (1994), S. 8167-8173

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: In this study, we correlate various processing conditions with the magnetic properties of CoCrTa/Cr films by varying the substrate preheating, the substrate bias, and the composition of the magnetic target. High Hc CoCrTa/Cr films with thin Cr underlayers were produced by either preheating the substrate or by rf bias sputtering. We found that the sputtering temperature of the magnetic layer plays a far more important role in reducing intergranular exchange coupling and increasing Hc than does the CoCrTa/Cr crystallographic texture. The optimum condition for preparing high Hc films depends on the magnetic target composition. Even though the crystallographic texture does not control Hc, it does have an effect on the ΔM curve which is related to the noise properties of CoCrTa/Cr media. ΔM measurements indicate that {11¯01}Co /{110}Cr textured films may have slightly better noise properties than the films with {112¯0}Co /{200}Cr texture with similar Hc. © 1994 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.357868

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4

Digitale Medien

A transmission electron microscopy study of the (Sm,Pr)5Co19 phase (1990)

Shen, Y. ; Laughlin, D. E.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 67 (1990), S. 7510-7513

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Transmission electron microscopy has been used to characterize the rhombohedral 5:19 phase (R3¯m) in a stoichiometric (Sm0.75Pr0.25)5Co19 alloy. In some regions, strain-induced contrast was observed in the 5:19 phase. By contrast analysis, this strain contrast was associated with a displacement vector of the type (1)/(3) [011¯0]. In other regions where the strain-induced contrast was significantly reduced, faults with the crystal structure of hexagonal (Sm,Pr)2Co7(2:7H) phase (P63/mmc) were observed. The formation of the faults is believed to release elastic energy within the 5:19 phase. In the interface regions between the 5:19 phase and the minor component hexagonal 2:7H phase, it was found by lattice imaging that the 5:19 and 2:7H plates are superimposed with a common c direction. The orientation relationship between the 5:19 and 2:7H phases is given by [0002]2:7H(parallel)[0003]5:19R and [112¯0]2:7H(parallel)[112¯0]5:19R.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.345811

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5

Digitale Medien

Large change of the giant magnetoresistance behavior after changing the spacer from Cu to CuMn alloy in Co/spacer/Co structures (1999)

Wang, H. ; Jin, Q. Y. ; Zhou, S. M. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 85 (1999), S. 5030-5032

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The giant magnetoresistance (GMR) effects in sandwiched Co/Cu/Co and Co/CuMn/Co structures have been investigated. The GMR oscillates with the spacer thickness for both cases, but is nearly antiphased. With diluted Mn atoms in the Cu spacer, the GMR curve as a function of the magnetic field changes a lot, and the saturation/switching field for GMR can be reduced greatly compared with that in Co/Cu/Co systems. This may indicate one way to obtain a highly sensitive GMR. © 1999 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.370081

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6

Digitale Medien

A detachable semiconductor bolometer for heat pulses (1992)

Shen, Y. ; Boragno, C. ; Buatier de Mongeot, F. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 63 (1992), S. 3791-3792

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: A semiconductor detachable bolometer using a superconducting thin film as coupling medium is described. The film acts as a low pass band filter for the phonons having a frequency below the superconductive gap. A comparison between different coupling media is reported.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1143276

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7

Digitale Medien

Study of dynamics of diffusion and cluster formation of copper deposition on polyimide by optical second-harmonic generation (1992)

Zhang, J. Y. ; Shen, Y. R. ; Soane, D. S.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 71 (1992), S. 2655-2662

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We demonstrate that optical second-harmonic generation (SHG) can be successfully used for in situ study of metal/polymer interfaces. With this SHG technique, Cu cluster formation on polyimide by surface diffusion and Cu diffusion into polyimide have been investigated. The diffusion coefficients of Cu clusters into polyimide at various temperatures have been determined from the measured decay of SHG signal with time. The effects of temperature, cluster size, and surface modification on diffusion have also been examined. For T 〈 Tg, the surface diffusion of Cu on polyimide to form clusters dominates over the diffusion into the bulk. The latter process becomes competitive with increasing temperature. When T (approximately-greater-than) Tg, few large-size Cu clusters can be formed on the polyimide surface. Cu diffusion into polyimide bulk can be greatly impeded by either a monolayer of Ti or by Cu clusters implanted in polyimide beforehand. In this case, Cu can wet the modified surface and form an interface between Cu and polyimide with good adhesion.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.351037

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8

Digitale Medien

Picosecond optical parametric amplification in lithium triborate (1991)

Zhang, J. Y. ; Huang, J. Y. ; Shen, Y. R. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 58 (1991), S. 213-215

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We report the performance of a type-I lithium triborate (LBO) optical parametric amplifier pumped by 15 ps, 355 nm laser pulses. It is seen that with proper design, LBO can be as efficient as barium borate for such an application.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.104692

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9

Digitale Medien

Noncritically phase-matched second-harmonic generation and optical parametric amplification in a lithium triborate crystal (1991)

Huang, J. Y. ; Shen, Y. R. ; Chen, Chuangtian ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 58 (1991), S. 1579-1581

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We evaluate the potential of lithium triborate (LBO) temperature-tuned to achieve type-I noncritical phase matching, for picosecond high-power second-harmonic generation (SHG) and tunable optical parametric amplification (OPA). Pumped by 35 ps, 1.064 μm laser pulses, a conversion efficiency of 65% was obtained from SHG. The output of OPA, pumped by 0.532 μm was tunable from 0.75 to 1.8 μm with an efficiency better than 20%.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.105156

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10

Digitale Medien

Superconducting YBa2Cu3O7−δ thin films with three different orientations (1990)

Wang, X. K. ; Li, D. X. ; Li, D. Q. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 67 (1990), S. 4217-4220

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Epitaxial thin films of YBaCuO have been prepared with (1) the a axis perpendicular to (100) SrTiO3 ; (2) the c axis perpendicular to (100) SrTiO3 ; and (3) the [110] axis perpendicular to (110) SrTiO3. Films were fabricated using a multilayer deposition technique involving three electron guns containing Y, BaF2, and Cu under a pressure of 5×10−5 Torr of O2. As deposited films, which contained polycrystalline and amorphous regions, were later annealed in a furnace under a flowing O2-H2 O atmosphere. X-ray diffraction patterns as well as scanning electron microscopy and high-resolution electron microscopy images confirm that the films are highly oriented, essentially epitaxial. The a-axis oriented film exhibits zero resistance at 90 K and a critical current density of 2.9×106 A/cm2 at 4.2 K while the c-axis oriented film exhibits a Tc of 88 K and a Jc of 0.9×107 A/cm2 at 4.2K; the Jc values were determined magnetically. The [110]-orientation film shows the sharpest transition with a transition width of 1 K and zero resistance at 85 K.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.344932

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