354 research outputs found
Reply to Comment "Invalidity of classes of approximate Hall effect calculations."
We reply to the criticism raised by Ao in his Comment (cond-mat/9801180).
Being unable to properly treat the Hall conductivity in a mixed state of
superconductors, Ao is looking for possible mistakes in microscopic and
phenomenological calculations, as well as in the corresponding experiments. The
errors in his treatment of the problem (cond-mat/9704247) are analized. We
indicate where the approach advocated by him fails to properly account for the
interaction with impurities and other sources of relaxation.Comment: reply to Comment by Ao (cond-mat/9801180) on our paper in PRL, 79,
1377 (1997), revtex file, 1 page, no figure
Spectral flow in superconducting point contacts
We find that multiple Andreev reflections mediating the transport in
superconducting point contacts are strongly affected by a small amount of
impurities in the area of the contact. We also argue that the model based on
Zener transitions within independent conducting channels is not suitable for
kinetic processes in multichannel contacts.Comment: Revised version. To be published in Europhysics Letter
Dynamic vortex mass in clean Fermi superfluids and superconductors
We calculate the dynamic vortex mass for clean Fermi superfluids including
both s- and d-wave superconductors as a response to a vortex acceleration.
Assuming a finite quasiparticle mean free time, the vortex mass appears to be a
tensor. The diagonal component dominates in the limit of long mean free time
while the off-diagonal mass takes over in the moderately clean regime.Comment: 4 pages, no figures, typeset using RevTe
Coulomb-enhanced resonance transmission of quantum SINIS junctions
Coherent charge transfer through a ballistic gated SINIS junction is mediated
by the resonant tunneling via the Andreev states. Extra charge accommodated on
the Andreev levels partially compensates the charge induced by the gate voltage
preserving the electron wavelength and maintaining the resonance conditions in
a broad range of gate voltages. As a result, the transparency of the junction
as well as the supercurrent trough it can be substantially increased as
compared to the zero-Coulomb case
Rotating vortex core: An instrument for detecting the core excitations
Effects of fermionic zero modes (bound states in a vortex core) on the
rotational dynamics of vortices with sponaneously broken axisymmetry are
considered. The results are compared with the Helsinki experiments where the
vortex cores were driven to a fast rotation and torsional oscillations by an
NMR r.f. field (Kondo et al, Phys. Rev. Lett. 67, 81 (1991)). We predict a
resonance NMR absorption on localized states at the external frequency
comparable with the interelevel distance, which is similar to the cyclotron
Landau damping. The resonances can experimentally resolve the localized levels
in vortex cores. For a pure rotation of the core, the effect depends on the
relative signs of the vortex winding number and of the core rotation; thus it
is sensitive to the direction of rotation of the container. The similarity with
the fermionic zero modes on the fundamental strings, which simulate the
thermodynamics of black holes, is discussed.Comment: RevTex file, 7 pages, 1 Figure, extended and clarified after referee
Reports, to appear in Phys. Rev.
Surface superconductivity in multilayered rhombohedral graphene: Supercurrent
The supercurrent for the surface superconductivity of a flat-band
multilayered rhombohedral graphene is calculated. Despite the absence of
dispersion of the excitation spectrum, the supercurrent is finite. The critical
current is proportional to the zero-temperature superconducting gap, i.e., to
the superconducting critical temperature and to the size of the flat band in
the momentum space
Magnetic quantization of electronic states in d-wave superconductors
We derive a general quasiclassical approach for long-range magnetic-field
quantization effects in superconductors. The method is applied to superclean
d-wave superconductors in the mixed state. We study the delocalized states with
energies . We find that the energy
spectrum consists of narrow energy bands whose centers are located at the
Landau levels calculated in absence of the vortex potential. We show that
transitions between the states belonging to the different Landau levels give
rise to resonances in the a.c. quasiparticle conductivity and in the a.c.
vortex friction.Comment: 11 pages, no figure
Resonance energy and charge pumping through quantum SINIS contacts
We propose a mechanism of quantum pumping mediated by the spectral flow in a
voltage-biased SINIS quantum junction and realized via the sequential closing
of the minigaps in the energy spectrum in resonance with the Josephson
frequency. We show that the dc current exhibits giant peaks at rational
voltages
Nonequilibrium phenomena in multiple normal-superconducting tunnel heterostructures
Using the nonequilibrium theory of superconductivity with the tunnel
Hamiltonian, we consider a mesoscopic NISINISIN heterostructure, i.e., a
structure consisting of five intermittent normal-metal (N) and superconducting
(S) regions separated by insulating tunnel barriers (I). Applying the bias
voltage between the outer normal electrodes one can drive the central N island
very far from equilibrium. Depending on the resistance ratio of outer and inner
tunnel junctions, one can realize either effective electron cooling in the
central N island or create highly nonequilibrium energy distributions of
electrons in both S and N islands. These distributions exhibit multiple peaks
at a distance of integer multiples of the superconducting chemical potential.
In the latter case the superconducting gap in the S islands is strongly
suppressed as compared to its equilibrium value
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