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  • 1
    Electronic Resource
    Electronic Resource
    Discovery of the acoustic Faraday effect in superfluid 3 He-B (1999)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 400 (1999), S. 431-433 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Acoustic waves provide a powerful tool for studying the structure of matter. For example, the speed, attenuation and dispersion of acoustic waves can give useful information on molecular forces and the microscopic mechanisms of absorption and scattering of acoustic energy. In solids, both ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/22712
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamics of ad-wave superconductor near a surface (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 1079-1098 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the properties of an anisotropically paired superconductor in the presence of specularly reflecting surface. The bulk stable phase of the superconducting order parameter is taken to have dx2-y2 symmetry. Contributions by order parameter components of different symmetries vanish in the bulk, but may enter in the vicinity of a wall. We calculate the self-consistent order parameter and surface free energy within the quasiclassical formulation of superconductivity. We discuss, in particular, the dependence of these quantities on the degree of order parameter mixing and the surface to lattice orientation. Knowledge of the thermodynamically stable order parameter near a surface is a necessary precondition for calculating measurable surface properties which we present in a companion paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754525
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal Conductivity of the Accidental Degeneracy and Enlarged Symmetry Group Models for Superconducting UPt3 (1999)
    Springer
    Journal of low temperature physics 114 (1999), S. 257-273 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present theoretical calculations of the thermal conductivity for the “accidental degeneracy” and “enlarged symmetry group” models that have been proposed to explain the phase diagram of UPt 3 . The order parameters for these models possess point nodes or cross nodes, reflecting the broken symmetries of the ground state. These broken symmetries lead to robust predictions for the ratio of the low-temperature thermal conductivity for heat flow along the ĉ axis and in the basal plane. The anisotropy of the heat current response at low temperatures is determined by the phase space for scattering by impurities. The measured anisotropy ratio, κ c/κ b, provides a strong constraint on theoretical models for the ground state order parameter. The accidental degeneracy and enlarged symmetry group models based on no spin-orbit coupling do not account for the thermal conductivity of UPt 3. The models for the order parameter that fit the experimental data for the ĉ and $${\hat c}$$ directions of the heat current are the 2D E1g and E 2u models, for which the order parameters possess line nodes in the ab-plane and point nodes along the ĉ axis, and the A1g⊕E 1g model of Zhitomirsky and Ueda. This model spontaneously breaks rotational symmetry in the ab-plane below Tc2 and predicts a large anisotropy for the ab-plane heat current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021814206687
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  • 4
    Electronic Resource
    Electronic Resource
    Circular dichroism and birefringence in unconventional superconductors (1992)
    Springer
    Journal of low temperature physics 86 (1992), S. 257-290 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a theoretical analysis of circular dichroism and birefringe in unconventional BCS superconductors with appropriate broken symmetries. We show that for the effect to exist, that in addition to broken time-reversal and two-dimensional parity symmetries, it is necessary to take into account the weak particle-hole asymmetry of the low-energy excitations of the metallic state. Circular dichroism and birefringence are shown to arise from the order parameter collective mode response of the superconductor; in the clean limit the contribution to the current response from the single-particle excitations does not give rise to circular dichroism or birefringence, even with particle-hole asymmetry. The magnitude of the circular dichroism is found to be small for the classes of superconductors which are thought to be likely candidates to exhibit the requisite broken symmetries, namely the heavy fermions and oxide superconductors. The order of magnitude of the elliptical polarization of a linearly polarized incident wave is Vf/c(ζ/λL) (Δ/Ef) ln(Ef/Δ), which is roughly 10−7−10−8 rad at frequencies of order the gap, and decreases at least as fast as (2Δ/ω)2 at higher frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01151804
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  • 5
    Electronic Resource
    Electronic Resource
    Comment on the coupling of zero sound to theJ=1− modes of3He-B (1993)
    Springer
    Journal of low temperature physics 90 (1993), S. 337-341 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Features in the zero sound attenuation near the pair-breaking edge in superfluid3He-B have been observed in large magnetic fields. Schopohl and Tewordt [J. Low Temp. Phys. 57, 601 (1984)] claim that theJ=1−,M=±1 order-parameter collective modes couple to zero sound as a result of the distortion of the equilibrium order parameter by a magnetic field; they identify the new features with these modes. However, we show that, when the effect of gap distortion on the collective modes is properly taken into account, the collective modes equations of Schopohl and Tewordt yield no direct coupling of zero sound to theJ=1− modes. Thus, the identification of the absorption features reported by Ling, Saunders, and Dobbs [Phys. Rev. Lett. 59, 461 (1987)] near the pair-breaking edge with theJ=1 − modes is not clearly established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00681885
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  • 6
    Electronic Resource
    Electronic Resource
    Transverse waves in superfluid3He-B (1993)
    Springer
    Journal of low temperature physics 91 (1993), S. 13-37 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We examine the theory of collisionless transverse current waves in bulk superfluid3He-B, including the coupling to the order parameter collective modes. At low frequencies, Ω ≪ δ(T), the order parameter modes do not contribute to the restoring force for a transverse current, and the quasiparticle contribution drops rapidly as the gap in the spectrum develops. Thus, low-frequency transverse sound becomes overdamped at temperatures nearT c . However, at low temperatures (T ≲0.3T c ) the off-resonant coupling to the J = 2−,M = +-1 modes stabilizes a propagating transverse current mode, with a large phase velocity and low damping for frequencies above a critical frequency that is approximately that of theJ = 2 − mode. We also discuss the similarities and differences of longitudinal and transverse sound in the superfluid phases. For example, in zero field, right- and left-circularly polarized waves are degenerate. A magnetic field, with $$\overrightarrow \operatorname{H}||\overrightarrow {\text{q}}$$ , lifts this degeneracy, giving rise to the analog of circular dichroism and birefringence of electromagnetic waves. Thus, transverse waves may be more easily detected in the B-phase than in normal3He.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00132087
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  • 7
    Electronic Resource
    Electronic Resource
    A theory for the superconducting phases of UPt3 (1994)
    Springer
    Journal of low temperature physics 95 (1994), S. 153-168 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract I discuss a phenomenological theory for the multiple superconducting phases of UPt3 that is based on an order parameter belonging to an orbital 2D representation of the hexagonal point group which is coupled to a weak symmetry breaking field. I show that (1) the existing H-T and P-T phase diagrams (including an apparent tetracritical point in the H-T plane for all field orientations), (2) the anisotropy of the upper critical field over the full temperature range, (3) the correlation between superconductivity and basal plane antiferromagnetism and (4) low-temperature power laws in the transport and thermodynamic properties can be explained qualitatively, and in many respects quantitatively, by an odd-parity, E2u order parameter with a pair spin projection of zero along the ĉ-axis. AFM ordering in the basal plane, which couples to the superconducting order parameter, acts as the symmetry breaking field that is responsible for both the apparent tetracritical point and the zero-field double transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754932
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal conductivity of superconducting UPt3 at low temperatures (1997)
    Springer
    Journal of low temperature physics 106 (1997), S. 727-727 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395934
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  • 9
    Electronic Resource
    Electronic Resource
    Thermal conductivity of superconducting UPt3 at low temperatures (1996)
    Springer
    Journal of low temperature physics 102 (1996), S. 367-379 
    Details
    ISSN: 1573-7357
    Keywords: 74.25.Fy ; 74.70.Tx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the thermal conductivity within the E1g and E2u models for superconductivity in UPt3 and compare the theoretical results for electronic heat transport with recently measured results reported by Lussier, Ellman and Taillefer. The existing data down to T/Tc ≈ 0.1 provides convincing evidence for the presence of both line and point nodes in the gap, but the data can be accounted for either by an E1g or E2u order parameter. We discuss the features of the pairing symmetry, Fermi surface, and excitation spectrum that are reflected in the thermal conductivity at very low temperatures. Significant differences between the E1g and E2u models are predicted to develop at excitation energies below the bandwidth of the impurity-induced Andreev bound states. The zero-temperature limit of the ĉ axis thermal conductivity, limT→0 kc/T, isuniversal for the E2u model, but non-universal for the E1g model. Thus, impurity concentration studies at very low temperatures should differentiate between the nodal structures of the E2u and E1g models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00755120
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  • 10
    Electronic Resource
    Electronic Resource
    The effect of surfaces on the tunneling density of states of an anisotropically paired superconductor (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 1099-1121 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present calculations of the tunneling density of states in an anisotropically paired superconductor for two different sample geometries: a semi-infinite system with a single specular wall, and a slab of finite thickness and infinite lateral extent. In both cases we are interested in the effects of surface pair breaking on the tunneling spectrum. We take the stable bulk phase to be of dx 2−y2 symmetry. Our calculations are performed within two different band structure environments: an isotropic cylindrical Fermi surface with a bulk order parameter of the form Δ ∼ k x 2 −k y 2 , and a nontrivial tight-binding Fermi surface with the order parameter structure coming from an antiferromagnetic spin-fluctuation model. In each case we find additional structures in the energy spectrum coming from the surface layer. These structures are sensitive to the orientation of the surface with respect to the crystal lattice, and have their origins in the detailed form of the momentum and spatial dependence of the order parameter. By means of tunneling spectroscopy, one can obtain information on both the anisotropy of the energy gap, ¦Δ(p)¦, as well as on the phase of the order parameter, Δ(p) = ¦Δ(p)¦ eiϕ(p).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754526
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