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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3407-3410 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the effects of ozone oxygenation of YBa2Cu3O7−δ thin crystals for eliminating local fluctuation in oxygen content, which is known to exist even in normal δ≈0 samples. An optimum ozone annealing condition was determined based on the microstructure and the uniformity of oxygen content of the samples. We observed the formation of fine-spacing twins running perpendicular to the original twins at thin areas and attributed this to accommodating the local strain due to oxygen uptake during ozone annealing.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6099-6101 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic properties of easy-plane spin-one Heisenberg ferromagnet, H=D∑i(Six)2 −J∑(i,j)Si⋅Sj−h∑iSiz, are investigated using the linked cluster series expansion. The results of the linked cluster series expansion method cover the whole range of temperatures, both magnetically ordered and disordered phases. The order parameter is included in correlations of spin fluctuation and solved self-consistently to high orders. The magnetization as a function of temperature for a given value of easy-plane anisotropy is shown. The observed values of magnetization from the linked cluster series expansion are appreciably depressed from their mean-field approximation values due to the quantum and thermal fluctuations. The effects of the quantum fluctuation on the magnetic ordering in three-dimensional (3D) systems are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6108-6108 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using the coupled-cluster method we investigate the ground-state properties of an easy-plane spin-one antiferromagnet which has a critical point at zero temperature. This spin system represents a nontrivial system with the single-ion anisotropy. Single-ion anisotropies have a fundamental influence on the behavior of a magnetic system, and prevail in almost all physical systems with spin greater than one half. Because of the complexities caused by the single-ion anisotropy term, the mean-field approximation is commonly used in calculations of the thermodynamic quantities. However, in the mean-field approximation both quantum and spin fluctuation correlations have been neglected. Here we apply the coupled-cluster method to obtain the ground-state energy, staggered magnetization and critical point for both two and three dimensional lattices. In the coupled-cluster method the correlations of the quantum and spin fluctuations have been systematically included.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5485-5487 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The mean-field approximation of the critical behavior of the antiferromagnetic Ising model in a magnetic field shows that the critical field increases first at low temperature. However, the exact solution of a decorated square lattice proves that the critical field rapidly decreases with increasing temperature for the two-dimensional lattice. Three-dimensional lattices of this model have been studied as well using the high temperature expansion, low temperature expansion, and Monte Carlo simulation. The results are different. In this article we have investigated the critical field of the body centered cubic lattice of this model using the linked-cluster expansion technique. An eighth-order perturbation series for the free energy has been calculated. The magnetization and staggered magnetic susceptibility series have been calculated from the free energy. These series have been analyzed using Padé approximants to obtain the phase diagram in the field-temperature plane. A comparison is made with Monte Carlo simulation calculations.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6080-6082 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we have investigated the ground state of an easy-plane spin-one ferromagnet: H = D∑i(Sxi)2 −(J/2)∑(i, j)Si⋅Sj −h∑iSzi, using the coupled-cluster method. The mean-field approximation is commonly used in calculations of thermodynamic quantities for such systems because of the complexities caused by the single-ion anisotropy term. However, in the mean-field approximation both quantum and spin fluctuation correlations are neglected. Above the critical point, the zero-temperature series expansion method has been used to obtain estimates of the critical crystal field potential (Dc) and critical exponent of the susceptibility. Using the coupled-cluster method we obtained the ground-state energy, magnetization and critical point for both two- and three-dimensional lattices.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5461-5462 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dc hysteresis behavior of the magnetization and the 60-Hz ac loss characteristics were both measured at 4.2 K as a function of applied field to 2000 Oe on Yba2Cu3O7 and on iron-substituted YBa2(Cu1−xFex)3O7 samples with x=0.04 and 0.10. From the dc hysteresis behavior, energy loss per cycle was found to decrease with increasing Fe content. On the other hand, replacing copper with iron up to 4% did not change the 60-Hz loss, but increasing the iron content up to 10% was found to increase the loss by a significant amount.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3122-3132 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural properties of superconducting (Bi,Pb)2Sr2Ca2Cu3O10–Ag (2223) tapes have been measured using synchrotron x-ray scattering techniques. The x-ray photon energy was tuned just below the silver K absorption edge so the penetration depth was large, which allowed the measurements to be performed in a transmission geometry without removing the silver cladding. Analysis of the peaks in 2θ scans indicates that residual (Bi,Pb)2Sr2CaCu2O8 (2212) superconductor starting material is present in all samples studied. The amount of 2212 varied widely among the tapes, and was not homogeneous along the length of each individual tape. Residual 2212 content increased near the ends of most samples, suggesting that 2223 phase development is sensitive to whether the superconducting material is encased in silver or not. The bulk c-axis alignment was measured in ∼100 mono- and multifilament samples, and correlations between c-axis alignment and current carrying capacity at 77 K were found. Multifilament samples generally had better alignment than monofilament samples. The c-axis alignment along the length of the tapes was uniform, and the superconducting material within ∼1 μm of the Ag was better textured than the bulk of the sample. Intermediate pressings were directly shown to have an adverse affect on c-axis alignment. Finally, the evolution of texture and phase development was examined in a series of samples annealed for varying times. The 2212 starting material acquired the final c-axis alignment state after brief heating times, and only after much longer heating times did the 2212 transform into the 2223 phase. These results and their implications for improving processing procedures are discussed. © 1996 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1864-1866 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe, for the first time, the preparation of InGaAs/InP homojunction confined buried-heterostructure lasers by high vacuum processing techniques. Lithography and waveguide mesa etching were carried out using ultrathin native oxide masking, focused Ga ion beam writing, and free Cl2 etching. Base laser structures and overgrowth were carried out by atmospheric pressure metalorganic vapor phase epitaxy. The resulting lasers have low-threshold currents of ∼62 mA.
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 27 (1988), S. 6348-6353 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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