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  • 1
    Electronic Resource
    Electronic Resource
    Role of epitaxy and polycrystallinity in the magnetoresistance and magnetization of La0.8Sr0.2MnO3 thin films : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5169-5171 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: La0.8Sr0.2MnO3 thin films were simultaneously deposited by pulsed laser ablation on silicon (Si) and LaAlO3 (LAO) substrates. Films on Si were polycrystalline while those on LAO were (100) epitaxial with an in-plane correlation length of ≈10 nm. The magnetization and magnetoresistance behavior of these two films were significantly different. Both films exhibit antiferromagnetic–ferromagnetic transitions—at different temperatures [180 K (LAO); 230 K (Si)]—and their magnetic moments at 10 K were significantly different (Si—0.0035 emu; LAO—0.0022 emu). However, both films showed significant high field slope in magnetization at 10 K. Significant fractions of both films remain antiferromagnetic at low temperatures and hence net susceptibilities, dependent on the direction of the applied magnetic field, are different for the epitaxial (LAO) and randomly oriented polycrystalline (Si) films. The magnetoresistance peak, corresponding to the semiconductor–metal transition is observed at 170 and 130 K for the epitaxial (LAO) and polycrystalline (Si) films, respectively. Moreover, their resistance values are two orders of magnitude different (Si—MØhms; LAO—KOhms). These properties can be interpreted in terms of the major role of grain boundaries in determining the scattering as well as possible differences in O2 stoichiometry. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361919
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  • 2
    Electronic Resource
    Electronic Resource
    Direct observation of interface and surface steps in epitaxial films by dark-field transmission electron microscopy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1766-1768 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used dark-field transmission electron microscopy to investigate 〈5 nm thick CaF2 films grown on Si(111) by molecular-beam epitaxy. Images formed with CaF2 [111¯] reflections exhibit contrast at 1/3[111] height steps at the CaF2 surface and at the CaF2/Si interface over large ((approximately-greater-than)100 μm2), statistically significant areas. Direct evidence for step-flow growth in CaF2 has been obtained. © 1994 American Institue of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112912
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  • 3
    Electronic Resource
    Electronic Resource
    Microstructure and magnetic anisotropy of ultrathin Co/Pt multilayers grown on GaAs (1¯1¯1¯) by molecular-beam epitaxy (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5799-5807 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Multilayers of (Co3 A(ring), Pt15 A(ring))x, x=15 or 30 repeats, with or without a 200 A(ring) silver buffer layer, were grown on GaAs (111) substrates by molecular-beam epitaxy. Vibrating sample magnetometry measurements confirmed that the samples with the Ag buffer layer show strong uniaxial magnetic anisotropy perpendicular to the surface. The perpendicular anisotropy exhibited by these metallic superlattices is discussed in terms of the microstructure of the overall multilayer stack, as well as the structural characteristics of the Co interface layer. Samples grown on the Ag buffer layer show strong (111) texture with 30–40-nm-size twin-related grains. These grains, correspond to the two possible (111) stacking sequence for an fcc lattice, i.e., double positioning. However, direct growth on GaAs (111) results in randomly oriented 10–20 nm grains. All samples exhibit a repeat period of 1.83 nm in both low-angle reflectivity and high-angle aitch-theta–2aitch-theta x-ray scattering measurements. In addition, transverse scans through the low-angle multilayer Bragg peaks show the interfaces to be diffuse in nature indicative of considerable in-plane inhomogeneity and/or compound formation. High-resolution electron microscopy measurements of cross sections compared with image simulations confirm that the interface layer is diffuse and its stoichiometry is such that the Co occupation is less than 40%. Redistribution of Co should then extend over at least four monolayers. The nanostructure of the samples grown with the Ag buffer layer comprises an eight atomic layer repeat with the Co interface layer diffuse over four monolayers. The microstructure is strongly (111) textured with columns of twin related 30-nm-sized grains. It is suggested that the combination of interdiffusion, highly oriented but twin-related columnar growth, small grain size with a possible nanometer-scale second phase may be the key to the understanding of the perpendicular anisotropy observed in these (111) superlattices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351934
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of nanometer-scale epitaxial structures by grazing-incidence x-ray diffraction and specular reflectivity (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1936-1941 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray rocking curve analysis is a powerful and nondestructive technique for the characterization of heteroepitaxial structures. Conventionally, measurements are performed in symmetrical scattering geometry using a double-crystal x-ray diffractometer but the technique can be extended to the study of very thin layers (〈200 A(ring)) by the use of glancing-incidence scattering geometry and a triple-crystal diffractometer. These structures can also be studied by the technique of total external x-ray reflectivity. This is sensitive to the electron-density profile of the heterostructure as a function of depth. By combining the above techniques we have found it possible to obtain structural information on layers as thin as 20 A(ring). Such measurements permit accurate measurement of individual layer thicknesses and interface roughnesses on the angstrom level. The lattice parameter strain can be obtained by modeling of the intensity distribution of the crystal truncation rod.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339895
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  • 5
    Electronic Resource
    Electronic Resource
    Quasi-one-dimensional CaF2 islands formed on Si(001) by molecular beam epitaxy (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2363-2365 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Quasi-one-dimensional CaF2 islands, 5–10 nm in both width and height and several μm in length, have been grown on Si(001) by molecular beam epitaxy. Using conventional and high resolution transmission electron microscopy we show that the islands grow in two symmetry-equivalent, {011} orientations and are bounded by {111} facets. The unusual island morphology is attributed to a low density of nucleation sites, the small lattice mismatch, and the anisotropic CaF2 surface energy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115859
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  • 6
    Electronic Resource
    Electronic Resource
    X-ray reflectivity measurements of the expansion of carbon films upon annealing (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2100-2102 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements have been made of the x-ray reflectivity from ultrathin, amorphous carbon films both before and after annealing. Analysis of the x-ray results indicates that annealing causes an increase in film thickness with a corresponding decrease in density. Such behavior is uncharacteristic of amorphous thin films and is interpreted as being due to changes in the interatomic bonding associated with transition to a more graphitic microstructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106093
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  • 7
    Electronic Resource
    Electronic Resource
    New insight into the structure and growth of CaF2/Si(111) (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2071-2073 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used transmission electron microscopy and x-ray crystal truncation rod measurements to investigate thin (〈50 A(ring)) CaF2 films grown on Si(111) substrates by molecular beam epitaxy. The results indicate that CaF2/Si can be structurally as perfect as NiSi2/Si and CoSi2/Si, and that a reconstructed layer is present at the CaF2/Si(111) interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107092
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  • 8
    Electronic Resource
    Electronic Resource
    The XMaS beamline at ESRF: instrumental developments and high-resolution diffraction studies (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 1172-1181 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The beamline, which is situated on a bending magnet at ESRF, comprises a unique combination of instrumentation for high-resolution and magnetic single-crystal diffraction. White-beam operation is possible, as well as focused and unfocused monochromatic modes. In addition to an eleven-axis Huber diffractometer, which facilitates simple operation in both vertical and horizontal scattering geometries, there is an in-vacuum polarization analyser and slit system, mirrors for harmonic rejection, sub 4.2 K and 1 Tesla magnetic field sample environment, plus a diamond phase plate for polarization conditioning. The instrumentation developed specifically for this beamline is described, and its use illustrated by recent scientific results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049501015394
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  • 9
    Electronic Resource
    Electronic Resource
    The resolution function of an X-ray triple-crystal diffractometer: comparison of experiment and theory (1989)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 45 (1989), S. 416-422 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The resolution function of an X-ray triple-crystal diffractometer on a rotating-anode source has been studied both experimentally and theoretically. Three different experimental configurations were used, with perfect germanium, distorted germanium and pyrolytic graphite as monochromator and analyser, leading to changes in the resolution of two orders of magnitude. The results are compared with a Gaussian description of the resolution function and it is found that this describes the width of the central part with an accuracy of better than 25%. The wings of the resolution in the high-resolution mode show the effect of the non-Gaussian resolution elements but these are reproduced by a full numerical convolution theory of the resolution function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876738900108X
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  • 10
    Electronic Resource
    Electronic Resource
    Expression of extraocular myosin heavy chain in rabbit laryngeal muscle (1995)
    Springer
    Journal of muscle research and cell motility 16 (1995), S. 368-378 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intrinsic laryngeal muscles of mammals are functionally heterogeneous, some of these muscles (e.g. the thyroarytenoid) contract extremely rapidly, like extraocular muscle, whilst others (e.g. the cricothyroid) contract as fast as limb fast muscle. The extraordinarily rapid contraction speed of extraocular muscles is associated with a fast myosin not found in limb muscles. In this work we explored the possibility that the thyroarytenoid muscle may also express this extraocular-specific fast myosin by raising a monoclonal antibody (mab 4A6) against its heavy chain. Electrophoretic separation of native isomyosins revealed that both the extraocular and the thyroarytenoid have two similar bands migrating ahead of bands found in limb fast or cricothyroid myosins. These two bands bound mab 4A6. The thyroarytenoid muscle can be divided into two divisions, a vocalis division which is important in phonation and an external division which functions in closing the glottis. Fibres in the vocalis are heterogeneous, some stain with mab 4A6, whilst others stain with mabs against limb myosin heavy chains. Fibres in the external division stain almost homogeneous with mab 4A6. The immunohistochemical staining pattern in the cricothyroid muscle resembled that of fast limb muscle: no fibres stained with mab 4A6. Thus, the high speed of contraction of the thyroarytenoid is associated with the same myosin heavy chain found in extraocular muscles, this characteristic is presumably an evolutionary adaptation for rapid closure of the glottis to enhance airway defense mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00114502
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