Search Results - (Author, Cooperation:J. R. Kirtley)

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  1. 1
    Y. H. Wang ; J. R. Kirtley ; F. Katmis ; P. Jarillo-Herrero ; J. S. Moodera ; K. A. Moler
    American Association for the Advancement of Science (AAAS)
    Published 2015
    Staff View
    Publication Date:
    2015-08-15
    Publisher:
    American Association for the Advancement of Science (AAAS)
    Print ISSN:
    0036-8075
    Electronic ISSN:
    1095-9203
    Topics:
    Biology
    Chemistry and Pharmacology
    Computer Science
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Staff View
    Publication Date:
    2013-10-08
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  3. 3
    Petrov, D. K. ; Gupta, A. ; Kirtley, J. R. ; Krusin-Elbaum, L.

    [S.l.] : American Institute of Physics (AIP)
    Published 1998
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    We have developed a magnetic imaging scheme using the magnetoresistive spin valve head in a dc bias mode as a sensing element. By scanning the head in contact with the sample we obtain a submicron spatial resolution map of the normal component of the magnetic field in the temperature range 4.2–300 K. The writing element of the sensor can be used to alter the local magnetic structure in a controlled way. This technique was applied to image the magnetic domain structure down to 77 K in patterned thin films of La0.67Sr0.33MnO3, known for their colossal magnetoresistance. A reorientation of single or multiple domains in the films was accomplished by applying a local magnetic field with the writing element, while the effect on magnetotransport was monitored with the simultaneous measurement of current–voltage characteristics. © 1998 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  4. 4
    Kirtley, J. R. ; Theis, T. N. ; Mooney, P. M. ; Wright, S. L.

    [S.l.] : American Institute of Physics (AIP)
    Published 1988
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    We have measured the generation-recombination noise from the donor-related DX centers in current biased GaAs/AlxGa1−xAs heterostructures from 1 Hz to 25 kHz and from 77 to 330 K. A significant noise contribution from these traps is observed even at Al mole fractions below 0.2, where the trap level is resonant with the conduction band. The activated behavior of the noise spectrum from this resonant level is very similar to that observed at higher Al mole fractions, when the level lies deep in the fundamental gap. This result can be predicted, based on the recently elucidated relationship of the trap level to the band structure of AlxGa1−xAs. In accordance with other experimental results, the noise spectra demonstrate that the emission and capture kinetics of the level are unperturbed by its resonance with the conduction band. We briefly discuss some implications of these results for heterostructure transistor design.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  5. 5
    Falcony, C. ; Kirtley, J. R. ; DiMaria, D. J. ; Ma, T. P. ; Chen, T. C.

    [S.l.] : American Institute of Physics (AIP)
    Published 1985
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Electroluminescence emission from indium-tin-oxide (ITO) and indium oxide films incorporated in a Si-rich SiO2-SiO2-ITO (In2O3) multiple-layer structure is reported. The light emitted has a peak at approximately 3.3 eV for ITO and at 2.6 eV for In2O3. The intensity of the light is found to depend on the applied electric field.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  6. 6
    Fein, A. P. ; Kirtley, J. R. ; Feenstra, R. M.

    [S.l.] : American Institute of Physics (AIP)
    Published 1987
    Staff View
    ISSN:
    1089-7623
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Electrical Engineering, Measurement and Control Technology
    Notes:
    A scanning tunneling microscope capable of operating at low temperatures, T=400 mK, and in high magnetic fields, B=8 T, is described. Accompanying electronics, under the control of an IBM PC/AT, provide routine spatially resolved spectroscopy, allowing characterization of properties such as superconducting energy gaps and local density of states on the surface. Data are presented to illustrate the usefulness of spatially resolved spectroscopy at low temperatures and in high magnetic fields.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  7. 7
    Kirtley, J. R. ; Ketchen, M. B. ; Stawiasz, K. G. ; Sun, J. Z. ; Gallagher, W. J. ; Blanton, S. H. ; Wind, S. J.

    Woodbury, NY : American Institute of Physics (AIP)
    Published 1995
    Staff View
    ISSN:
    1077-3118
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    We have combined a novel low temperature positioning mechanism with a single-chip miniature superconducting quantum interference device (SQUID) magnetometer to form an extremely sensitive new magnetic microscope, with a demonstrated spatial resolution of ∼10 μm. The design and operation of this scanning SQUID microscope will be described. The absolute calibration of this instrument with an ideal point source, a single vortex trapped in a superconducting film, will be presented, and a representative application will be discussed. © 1995 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  8. 8
    Jeffery, Mark ; Van Duzer, T. ; Kirtley, J. R. ; Ketchen, M. B.

    Woodbury, NY : American Institute of Physics (AIP)
    Published 1995
    Staff View
    ISSN:
    1077-3118
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Superconducting electronic circuits surrounded by various configurations of holes in the superconducting ground plane have been imaged using a high resolution scanning superconducting quantum interference device (SQUID) microscope. These data demonstrate that in the weak field limit continuous moats trap flux more effectively to protect the circuits than small holes in the same configuration. © 1995 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  9. 9
    Kirtley, J. R. ; Tsuei, C. C.

    Woodbury, NY : American Institute of Physics (AIP)
    Published 1999
    Staff View
    ISSN:
    1077-3118
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    We demonstrate a design for a scanning superconducting quantum interference device (SQUID) microscope in which the sample temperature can be varied over a large range. In this design, both sample and SQUID are in the same vacuum space, separated by a few microns. By firmly anchoring the SQUID to a low-temperature bath, the sample temperature can be changed while the SQUID remains superconducting. This allows magnetic imaging at varying sample temperatures with micron-scale spatial resolution and the sensitivity of a low-Tc SQUID. We demonstrate this approach by imaging the temperature dependence of Abrikosov vortices in thin films of the high-temperature superconductor YBa2Cu3O7−δ. We extract the in-plane penetration depth λab(T) in our samples from these measurements. © 1999 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  10. 10
    Woods, S. I. ; Ingvarsson, S. ; Kirtley, J. R. ; Hamann, H. F. ; Koch, R. H.

    Woodbury, NY : American Institute of Physics (AIP)
    Published 2002
    Staff View
    ISSN:
    1077-3118
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    A method for altering the local direction and angular dispersion of anisotropy in soft magnetic films using energetic ion irradiation is demonstrated. NiFe films 50 Å thick were irradiated with 200 keV Ar+ ions to doses between 1013 and 1016 ions/cm2, while a saturating magnetic field was applied to the samples. This annealing field defined the new anisotropy direction of the irradiated areas, and the irradiation process also led to changes in the angular dispersion of anisotropy orientation, as measured by angle-dependent remanence of magnetization. By appropriate masking of films, this technique has been used to pattern samples with small "anisotropy domains." © 2002 American Institute of Physics.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  11. 11
    DiMaria, D. J. ; Theis, T. N. ; Kirtley, J. R. ; Pesavento, F. L. ; Dong, D. W. ; Brorson, S. D.

    [S.l.] : American Institute of Physics (AIP)
    Published 1985
    Staff View
    ISSN:
    1089-7550
    Source:
    AIP Digital Archive
    Topics:
    Physics
    Notes:
    Electron heating in silicon dioxide (SiO2) at electric fields (approximately-less-than)5 MV/cm is demonstrated using three different experimental techniques: carrier separation, electroluminescence, and vacuum emission. Gradual heating of the electronic carrier distribution is demonstrated for fields from 5 to 12 MV/cm with the average excess energy of the distribution reaching (approximately-greater-than)4 eV with respect to the bottom of the SiO2 conduction band edge. Off-stoichiometric SiO2 (OS-SiO2) layers are shown to behave similarly to very thin SiO2((approximately-less-than)70 A(ring) in thickness) with a transition occurring from "cool'' to "hot'' electrons as the conduction mechanism changes from direct tunneling between silicon (Si) islands in the SiO2 matrix of the OS-SiO2 material to Fowler-Nordheim emission into the conduction band of the SiO2 regions. The relationship of electron heating to electron trapping, positive charge generation, interface state creation, and dielectric breakdown is treated. The importance of various scattering mechanisms for stabilizing the electronic field-induced heating in the SiO2 and preventing current runaway and impact ionization is discussed. Scattering may be due to disorder, trapped charges, and acoustical phonons, as well as longitudinal optical phonons.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  12. 12
    Wynn, Janice C. ; Gardner, Brian W. ; Lin, Yu-Ju ; Liang, Ruixing ; Hardy, W. N. ; Kirtley, J. R. ; Moler, K. A. ; Bonn, D. A.

    [s.l.] : Macmillian Magazines Ltd.
    Published 2001
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] There is a long-standing debate about whether spin–charge separation is the root cause of the peculiar normal-state properties and high superconducting transition temperatures of the high-Tc materials. In the proposed state of matter, the elementary excitations are not ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  13. 13
    Tsuei, C. C. ; Kirtley, J. R. ; Ren, Z. F. ; Wang, J. H. ; Raffy, H. ; Li, Z. Z.

    [s.l.] : Nature Publishing Group
    Published 1997
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] An s + d pair state in orthorhombic copper oxides such as YBa2Cu3O7_5 (YBCO) is characterized by a gap function A(k) that transforms like s(tfx + fy + d(tfx - *£), where hx and ky are components of the wavevector k, and s and d are measures of the amounts of s-wave and d-wave pairing in the ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  14. 14
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] One leading candidate theory of high-temperature superconductivity in the copper oxide systems is the interlayer tunnelling (ILT) mechanism. In this model, superconductivity is created by tunnelling of electron pairs between the copper oxide planes — contrasting with other models in which ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  15. 15
    Kirtley, J. R. ; Tsuei, C. C. ; Sun, J. Z. ; Chi, C. C. ; Yu-Jahnes, Lock See ; Gupta, A. ; Rupp, M. ; Ketchen, M. B.

    [s.l.] : Nature Publishing Group
    Published 1995
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] Possibly the single most controversial topic in solid-state physics today is the mechanism for high-Tc superconductivity. Of especial interest is the question of whether the interaction that forms Cooper pairs in the high-7^ superconductors is mediated by spin fluctuations. Although there is a ...
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  16. 16
    Tsuei, C. C. ; Kirtley, J. R.
    Springer
    Published 1997
    Staff View
    ISSN:
    1573-7357
    Keywords:
    74.72.Bk ; 74.60. Ge
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract An unambiguous determination of the pairing symmetry in cuprate superconductors is important in order to understand the origin of high-temperature superconductivity. By making use of the effects of pair tunneling and flux quantization, we have designed and implemented several tricrystal experiments for phase-sensitive determination of the order parameter symmetry in high-Tc superconductors such as YBa2Cu3O7 Tl2Ba2CuO6, GdBa2Cu3O7, and Bi2Sr2CaCu2O8. By using a high-resolution scanning SQUID microscope, we have made the first direct observation of spontaneously generated half-flux quanta at the tricrystal point. The half-integer flux quantum effect in various specially designed tricrystal cuprate systems provides strong evidence for d-wave pairing in high-Tc cuprates. Our various tricrystal experiments have demonstrated that this effect can be used as a general probe of the microscopic phase of the pair wavefunction in unconventional superconductors.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  17. 17
    Staff View
    ISSN:
    1572-9605
    Keywords:
    Symmetry ; tricrystal ; half-integer ; flux-quanta
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Electrical Engineering, Measurement and Control Technology
    Physics
    Notes:
    Abstract The presence or absence of the half-integer flux quantum effect in controlled orientation tricrystal grain boundary rings is a general test of the phase of the superconducting order parameter. One such test proves that this effect is symmetry dependent, and that the order parameter in YBa2Cu3O7-ς has lobes and nodes consistent with d-wave symmetry. Our measurements show that the flux in the 1/2 integer ground state is quantized to Φ0/2 within ± 3%. This puts limits on the imaginary component of the superconducting order parameter in YBa2Cu3O7-ς.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses