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Sy-Hwang Liou Publications

1996

Articles 1 - 5 of 5

Full-Text Articles in Physics

A Novel Multilayer Circuit Process Using Yba2cu3ox /Srtio3 Thin Films, H.Q. Li, R.H. Ono, L.R. Vale, D.A. Rudman, Sy_Hwang Liou Oct 1996

A Novel Multilayer Circuit Process Using Yba2cu3ox /Srtio3 Thin Films, H.Q. Li, R.H. Ono, L.R. Vale, D.A. Rudman, Sy_Hwang Liou

Sy-Hwang Liou Publications

A process combining hydrofluoric acid (HF) and Ar+ ion milling has been used to make YBa2Cu3Oχ/SrTiO3/YBa2Cu2Oχ (YBCO/STO/YBCO) multilayer test circuits. Low-angle steps can be readily etched in STO and YBCO films with this process. YBCO lines crossing 5° steps have about the same critical temperature Tc (89–90 K) and critical current density Jc (>1X106 A/cm2 at 86 K) as lines on planar surfaces. Via connections have the same Tc as other circuit components and adequate critical currents for most circuit …

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Superparamagnetic Magnetic Force Microscopy Tips, P.F. Hopkins, John Moreland, S.S. Malhotra, Sy_Hwang Liou Apr 1996

Superparamagnetic Magnetic Force Microscopy Tips, P.F. Hopkins, John Moreland, S.S. Malhotra, Sy_Hwang Liou

Sy-Hwang Liou Publications

We report on magnetic force microscopy (MFM) images of a thin-film magnetic recording head taken using batch micromachined silicon tips coated with nanocomposite Fe60 (SiO2)40 and Fe70 (SiO2)30 films. The small Fe grain size (<10 nm) and dilute Fe volume fraction (0.29–0.4) of these granular films produce tip coatings of low remanence and essentially zero coercivity, reduced by the superparamagnetic properties of these films. We have used these tips to obtain MFM images of the write field of the head with high spatial and magnetic-field resolution. In comparison to images taken using commercial Co85Cr15-coated tips, these MFM images show reduced tip memory effects and clearly delineate the gap field from the pole pieces.

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Magnetic Properties Of Nanometer-Size Copt Particles, Sy_Hwang Liou, Yi Liu, S.S. Malhotra, M. Yu, David J. Sellmyer Apr 1996

Magnetic Properties Of Nanometer-Size Copt Particles, Sy_Hwang Liou, Yi Liu, S.S. Malhotra, M. Yu, David J. Sellmyer

Sy-Hwang Liou Publications

We have prepared nanometer-size, isolated CoPt particles. The particles in the range of 100–300 nm in diameter were formed by annealing thin films in the temperature range of 550–800 °C. Films with magnetic coercivity as high as 30 kOe were achieved. The results indicate that the high magnetic coercivity was obtained because the crystallite size approaches that of noninteracting single-domain particles.

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High Coercivity Rare Earth–Cobalt Films, S.S. Malhotra, Yi Liu, Z.S. Shan, Sy_Hwang Liou, D.C. Stafford, David J. Sellmyer Apr 1996

High Coercivity Rare Earth–Cobalt Films, S.S. Malhotra, Yi Liu, Z.S. Shan, Sy_Hwang Liou, D.C. Stafford, David J. Sellmyer

Sy-Hwang Liou Publications

Rare earth–cobalt (RCo, R=Sm, Pr) films with thicknesses from 30 to 700 nm have been prepared with and without a Cr underlayer by dc magnetron sputtering from a R2Co7 composite target. The as-deposited SmCo films with a Cr underlayer (SmCo║Cr) have magnetic coercivities of about 500–2800 Oe and the PrCo║Cr films have coercivities of about 100–300 Oe, but after annealing at 500 °C coercivities as high as 31 kOe for SmCo║Cr films and 10 kOe for PrCo║Cr films were observed. The as-deposited PrCo films are composed mostly of an amorphous phase with about 30 vol % of …

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C-Axis Oriented (Hg,Ti)-Based Superconducting Films With TC≥125 K, F. Foong, B. Bedard, Q.L. Xu, Sy_Hwang Liou Feb 1996

C-Axis Oriented (Hg,Ti)-Based Superconducting Films With TC≥125 K, F. Foong, B. Bedard, Q.L. Xu, Sy_Hwang Liou

Sy-Hwang Liou Publications

Thin films with mostly (Hg,Tl) 1Ba2Ca3Cu2O8+ δ [(Hg,Tl)-1223] phase have been fabricated by radio frequency magnetron sputtering of precursor films and post-annealing method. The doping of a small amount of thallium in the film is helpful to the formation of the three-layer CuO2 compound. These films have a highly oriented structure with the c-axis perpendicular to the film surface. Resistivity measurements show that the films after annealing at 300 °C for 1 h in O2 have the superconducting transition temperature of Tc (onset)=133 K and Tc (zero)=127 …

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