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  • 1
    Electronic Resource
    Electronic Resource
    Two-dimensional nonequilibrium dynamics of domain-wall motion : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5757-5759 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamics of magnetic domain-wall motion in two dimensions for materials of interest to vertical Bloch-line memory devices has been simulated on the Connection Machine. By use of a Fourier transform technique to evaluate the demagnetizing fields and explicit time integration of the Landau-Lifshitz-Gilbert equation, the equilibrium configuration of a domain wall and the dynamic structure of a wall in the presence of an external field has been studied. Horizontal Bloch-line (HBL) nucleation, propagation and "punch through'' can be observed in moving walls. The domain-wall configuration for stripe chopping has been investigated and HBL motion is seen to be a dominant feature in this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347916
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  • 2
    Electronic Resource
    Electronic Resource
    A topological invariant for the accessibility problem of micromagnetics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5347-5349 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A singularity-free three-dimensional micromagnetic configuration is accessible from a given initial state if there is a continuous family of interpolating states. This paper proposes an integral formula for the accessibility invariant which classifies (up to homotopy) the possible final states which are inaccessible from a given initial state. For infinite samples, we give explicit formulas describing initial states from which the final state of uniform saturation cannot be accessed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344607
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  • 3
    Electronic Resource
    Electronic Resource
    Submillimeter optical properties of hexagonal boron nitride (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3962-3966 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The submillimeter optical properties of hot-pressed polycrystalline boron nitride with a predominantly hexagonal crystal structure were studied at room temperature from ∼20 to 120 cm−1 (λ=500–84 μm) with a Fourier-transform spectrometer. Several grades were studied and probed both parallel and perpendicular to the material's optic axis. The material was found to behave as a negatively uniaxial birefringent crystal. The birefringence, defined as the difference between the real part of the extraordinary and ordinary indices of refraction (ne–no), was quite large in one case with a value of −0.152. The material's absorption properties were also studied. For certain grades, a modest dichroism was observed. The low absorption (α〈1 cm−1) for grade A at frequencies below 38 cm−1 suggests the possibility for millimeter/submillimeter wave applications. Results are compared with data obtained by other researchers on related materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352860
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  • 4
    Electronic Resource
    Electronic Resource
    Coercivity mechanisms in magneto-optical recording media (abstract) : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5792-5792 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper is devoted to an explanation of why the coercivity is much lower than the macroscopic anisotropy field (Brown paradox). The effect of nanostructure on the nucleation coercivity Hnc and wall motion coercivity Hwc is investigated using connection machine simulations. The magneto-optical (MO) thin films with inhomogeneities are modeled by a patchy two-dimensional lattice. The patches have random shape and size; the anisotropy constant fluctuates randomly from patch to patch; the exchange strength is uniform within the patches, but fluctuates at the patch borders. We have simulated various nucleation and wall motion processes on more than a dozen patchy lattices, with the average patch size d ranging from 60 to 300 A(ring). In all cases the average domain wall width δ(approximately-equal-to)120 A(ring). Some of our results are the following: (i) As d increases, Hnc decreases fast for d〈δ, but slowly for d(approximately-greater-than)δ. (ii) Hnc decreases with decreasing exchange strength at the patch borders. (iii) Hwc in films of small patches (d≤δ) is greater than that in films of large patches (d(approximately-greater-than)δ). (iv) Hwc increases with decreasing exchange coupling at the patch borders. Our results show that the scale of inhomogeneity responsible for the low Hnc in MO thin films ranges from 100 to 200 A(ring). This work extends the previous work on nucleation1 and pinning2 mechanisms in several respects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353576
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  • 5
    Electronic Resource
    Electronic Resource
    Precision terahertz relative reflectometry using a blackbody source and heterodyne receiver (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 438-444 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Instrumentation for making localized, precise relative reflection measurements of metals and superconductors in the terahertz frequency range is demonstrated. The results can be used to determine the surface resistivity of these materials which is of particular importance to development of high-temperature superconductors. Emission from a commerically available 1000 °C blackbody source was reflected from the materials under test and a reference reflector. The reflected signals were detected by a Schottky diode heterodyne receiver using a CO2-laser-pumped 214.5 μm CH2F2 laser as the local oscillator. Double-sideband bandwidth and receiver noise temperature were 2 GHz and 30 000 K, respectively. The use of a broadband incoherent diagnostic source minimizes instrumentation sensitivity to coherent interference effects. The heterodyne receiver provides for sensitive detection with good spatial and frequency resolution. Unoptimized spatial resolution of four times the diffraction limit was achieved. The potential for relative reflectivity measurement accuracy of better than 0.1% was demonstrated with 30 min measurement times though systematic errors limited actual measurement accuracy to about 0.3%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145153
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  • 6
    Electronic Resource
    Electronic Resource
    An efficient three-dimensional demagnetizing field calculation scheme (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4685-4685 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an efficient three-dimensional demagnetizing field calculation scheme for micromagnetic simulations of the domain walls in garnet-like materials. We take advantage of the fact that the domain wall is nearly planar and distribute computational power nonuniformly between the bulk of the material and the wall regions. We use fast Fourier convolutions along one dimension (approximately parallel to the domain wall) and a two-dimensional variant of Greengard's adaptive fast multipole method in the other dimensions. Even a 2D nonadaptive multipole method has the time complexity of the order of N, for N points in contrast to full Fourier convolution (Nlog N) or direct methods (N2). The adaptive method is based on maintaining a point-to-point error bound which allows us to work at high resolution in the region of the domain wall and coarser resolution in the bulk material. In this case, the calculation scales proportional to the domain wall size rather than the sample volume. The error bound calculation is important for our method and it depends on the Gegenbauer's addition theorem for the modified Bessel functions. Due to the complex nature of this addition theorem, we have relied on numerical methods, comparing our method to the direct calculations for small size samples. We have implemented this scheme on an SGI workstation and we are reporting the outcome of the 2D adaptive fast multipole method implementation. We have studied the relationship between error bounds, domain wall size, and actual time. We have also compared our results with that of M. Redjdal's method. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361705
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  • 7
    Electronic Resource
    Electronic Resource
    Noncontact force microscopy in liquids (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 617-618 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Force microscopy in liquids offers many advantages including the mitigation of capillary forces and the simulation of real environments for biological and technological processes. Noncontact force microscopy in liquids adds the advantage of probing electrical and magnetic fields above surfaces. Here we demonstrate magnetic force imaging of recorded bits on a computer hard disk in air and in liquid. A method of noncontact force microscopy (patent pending, Digital Instruments) is used in which the tip is first scanned in contact to image topography and then rescanned above the surface to image long-range forces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109967
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  • 8
    Electronic Resource
    Electronic Resource
    Density and viscosity of mixtures of 1,1,2,2-tetrabromoethane and 1-bromododecane (1969)
    s.l. : American Chemical Society
    Journal of chemical & engineering data 14 (1969), S. 470-473 
    Details
    ISSN: 1520-5134
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/je60043a017
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  • 9
    Electronic Resource
    Electronic Resource
    Introduction - Waste Disposal in the Petroleum Industry (1954)
    s.l. : American Chemical Society
    Industrial & engineering chemistry 46 (1954), S. 283-283 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie50530a026
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  • 10
    Electronic Resource
    Electronic Resource
    Three-dimensional micromagnetic simulations on the connection machine (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5821-5823 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We are using the connection machine to perform three-dimensional micromagnetic simulations of films with interesting topological structures such as vertical Bloch lines. A critical element of the computations is the calculation of the demagnetizing field. We have extended the Fourier method of Mansuripur and Giles to three-dimensional films and implemented it on the connection machine. We discuss the algorithm and its parallel implementation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345975
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