1,187 research outputs found
Andreev spectroscopy and surface density of states for a three-dimensional time-reversal invariant topological superconductor
A topological superconductor is a fully gapped superconductor that exhibits
exotic zero-energy Andreev surface states at interfaces with a normal metal. In
this paper we investigate the properties of a three-dimensional time reversal
invariant topological superconductor by means of a two-band model with
unconventional pairing in both the inter- and intraband channels. Due to the
bulk-boundary correspondence the presence of Andreev surface states in this
system is directly related to the topological structure of the bulk
wavefunctions, which is characterized by a winding number. Using quasiclassical
scattering theory we construct the spectrum of the Andreev bound states that
appear near the surface and compute the surface density of states for various
surface orientations. Furthermore, we consider the effects of band splitting,
i.e., the breaking of an inversion-type symmetry, and demonstrate that in the
absence of band splitting there is a direct transition between the fully gapped
topologically trivial phase and the nontrivial phase, whereas in the presence
of band splitting there exists a finite region of a gapless nodal
superconducting phase between the fully gapped topologically trivial and
nontrivial phases.Comment: 7 pages, 4 figures, typos corrected, two footnotes adde
Spin-orbital coupling in a triplet superconductor-ferromagnet junction
We study a novel type of coupling between spin and orbital degrees of freedom
which appears at triplet superconductor-ferromagnet interfaces. Using a
self-consistent spatially-dependent mean-field theory, we show that increasing
the angle between the ferromagnetic moment and the triplet vector order
parameter enhances or suppresses the p-wave gap close to the interface,
according as the gap antinodes are parallel or perpendicular to the boundary,
respectively. The associated change in condensation energy establishes an
orbitally-dependent preferred orientation for the magnetization. When both gap
components are present, as in a chiral superconductor, we observe a first-order
transition between different moment orientations as a function of the exchange
field strength.Comment: 5 pages, 4 figures and Supplemental Material (3 pages
Classification and developmental biology of congenital anomalies of the hand and upper extremity
Selfconsistent gauge-invariant theory of in-plane infrared response of high-Tc cuprate superconductors involving spin fluctuations
We report on results of our theoretical study of the in-plane infrared
conductivity of the high-Tc cuprate superconductors using the model where
charged planar quasiparticles are coupled to spin fluctuations. The
computations include both the renormalization of the quasiparticles and the
corresponding modification of the current-current vertex function (vertex
correction), which ensures gauge invariance of the theory and local charge
conservation in the system. The incorporation of the vertex corrections leads
to an increase of the total intraband optical spectral weight (SW) at finite
frequencies, a SW transfer from far infrared to mid infrared, a significant
reduction of the SW of the superconducting condensate, and an amplification of
characteristic features in the superconducting state spectra of the inverse
scattering rate 1/tau. We also discuss the role of selfconsistency and propose
a new interpretation of a kink occurring in the experimental low temperature
spectra of 1/tau around 1000cm^{-1}.Comment: 9 pages with 6 figures, submitted to Physical Review
Renormalization of the elementary excitations in hole- and electron-doped cuprates due to spin fluctuations
Extending our previous studies we present results for the doping-, momentum-,
frequency-, and temperature- dependence of the kink-like change of the
quasiparticle velocity resulting from the coupling to spin fluctuations. In the
nodal direction a kink is found in both the normal and superconducting state
while in the antinodal direction a kink occurs only below due to the
opening of the superconducting gap. A pronounced kink is obtained only for
hole-doped, but not for electron-doped cuprates and is characteristically
different from what is expected due to electron-phonon interaction. We further
demonstrate that the kink structure is intimately connected to the resonance
peak seen in inelastic neutron scattering. Our results suggest similar effects
in other unconventional superconductors like .Comment: revised version, 12 pages, 19 figures. accepted for publication in
PR
Melt Production and Ejection From Lunar Intermediate-Sized Impact Craters: Where Is the Molten Material Deposited?
Differently aged impact melt in lunar samples is key to unveiling the early bombardment history of the Moon. Due to the mixing of melt products ejected from distant craters, the interpretations of the origin of lunar samples are difficult. We use numerical modeling for a better quantitative understanding of the production of impact-induced melt and in particular its distribution in ejecta blankets for lunar craters with sizes ranging from 1.5 to 50 km. We approximate the lunar stratigraphy with a porosity gradient, which represents the gradual transition from upper regolith via megaregolith to the solid crustal material. For this lunar setting, we quantify the melt production relative to crater volume and derive parameters describing its increasing trend with increasing transient crater size. We found that about 30%–40% of the produced melt is ejected from the crater. The melt concentration in the ejecta blanket increases almost linearly with distance from the crater center, while the thickness of the ejecta blanket decreases following a power law. Our study demonstrates that if in lunar samples the concentration of a melt with a certain age is interpreted to be of a nonlocal origin, these melts could be the impact products of a large crater (>10 km) located hundreds of kilometers away
0- transition in magnetic triplet superconductor Josephson junctions
We examine a Josephson junction involving two arbitrary equal-spin-pairing
unitary triplet superconductors and a ferromagnetic tunneling barrier. Using
perturbation theory, we show how the interaction of the barrier moment with the
spin of the tunneling triplet Cooper pairs can reverse the sign of the
Josephson charge current. This also results in a Josephson spin current, which
contains a phase-independent contribution due to reflection processes at the
barrier. We verify our analytic predictions using a non-perturbative
Bogoliubov-de Gennes method.Comment: 4 pages, 2 figures, RevTeX, version accepted to PR
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