104 research outputs found
Phase-locked magnetoconductance oscillations as a probe of Majorana edge states
We calculate the Andreev conductance of a superconducting ring interrupted by
a flux-biased Josephson junction, searching for electrical signatures of
circulating edge states. Two-dimensional pair potentials of spin-singlet d-wave
and spin-triplet p-wave symmetry support, respectively, (chiral) Dirac modes
and (chiral or helical) Majorana modes. These produce h/e-periodic
magnetoconductance oscillations of amplitude \simeq (e^{2}/h)N^{-1/2}, measured
via an N-mode point contact at the inner or outer perimeter of the grounded
ring. For Dirac modes the oscillations in the two contacts are independent,
while for an unpaired Majorana mode they are phase locked by a topological
phase transition at the Josephson junction.Comment: 10 pages, 6 figures. New appendix on the gauge invariant
discretization of the Bogoliubov-De Gennes equation. Accepted for publication
in PR
Phase Composition of Mo-Si-V Hypoeutectic Alloys
Thermodynamic modeling (TDM) of phase formation was performed with vanadium doping of the hypoeutectic Mo-Si alloy. It was found that the thermochemical properties of vanadium silicides (presented in the HSC Chemistry 6.12 database), when modeling Mo-Si(14.5-12.2)-V(5.0-20.0) alloys, lead to inadequate results regarding Mo-Si-V diagram state indicators. The simulation results agree satisfactorily with the Mo-Si-V diagram with the following values of ΔH0 298: for V3Si = - 180.4 kJ / mol, for V5Si3 = -433.6 kJ / mol, for VSi2 = -124.5 kJ / mol. According to the results of TDM and X-ray phase analysis (XRD) of the obtained alloys, it was found that vanadium in Mo-Si-V ternary alloys can be found both in the form of silicides, (Mo,V)3Si, and in the composition of the solid solution (Mo,V
Comment on Hess et al. Phys. Rev. Lett. {\bf 130}, 207001 (2023)
In this comment, we show that the model introduced in Hess et al. Phys. Rev.
Lett. {\bf 130}, 207001 (2023) fails the topological gap protocol (TGP)
(Pikulin et al., arXiv:2103.12217 and M. Aghaee et al., Phys. Rev. B 107,
245424 (2023)). In addition, we discuss this model in the broader context of
how the TGP has been benchmarked.Comment: Minor revision of the tex
Penetration of hot electrons through a cold disordered wire
We study a penetration of an electron with high energy E<<T through strongly
disordered wire of length L<<a (a being the localization length). Such an
electron can loose, but not gain the energy, when hopping from one localized
state to another. We have found a distribution function for the transmission
coefficient t. The typical t remains exponentially small in L/a, but with the
decrement, reduced compared to the case of direct elastic tunnelling. The
distribution function has a relatively strong tail in the domain of anomalously
high t; the average ~(a/L)^2 is controlled by rare configurations of
disorder, corresponding to this tail.Comment: 4 pages, 5 figure
Topological properties of superconducting junctions
Motivated by recent developments in the field of one-dimensional topological
superconductors, we investigate the topological properties of s-matrix of
generic superconducting junctions where dimension should not play any role. We
argue that for a finite junction the s-matrix is always topologically trivial.
We resolve an apparent contradiction with the previous results by taking into
account the low-energy resonant poles of s-matrix. Thus no common topological
transition occur in a finite junction. We reveal a transition of a different
kind that concerns the configuration of the resonant poles
Zero-voltage conductance peak from weak antilocalization in a Majorana nanowire
We show that weak antilocalization by disorder competes with resonant Andreev
reflection from a Majorana zero-mode to produce a zero-voltage conductance peak
of order e^2/h in a superconducting nanowire. The phase conjugation needed for
quantum interference to survive a disorder average is provided by particle-hole
symmetry - in the absence of time-reversal symmetry and without requiring a
topologically nontrivial phase. We identify methods to distinguish the Majorana
resonance from the weak antilocalization effect.Comment: 13 pages, 8 figures. Addendum, February 2014: Appendix B shows
results for weak antilocalization in the circular ensemble. (This appendix is
not in the published version.
~Green's function topology of Majorana wires
We represent the ~topological invariant characterizing a one
dimensional topological superconductor using a Wess-Zumino-Witten dimensional
extension. The invariant is formulated in terms of the single particle Green's
function which allows to classify interacting systems. Employing a recently
proposed generalized Berry curvature method, the topological invariant is
represented independent of the extra dimension requiring only the single
particle Green's function at zero frequency of the interacting system.
Furthermore, a modified twisted boundary conditions approach is used to
rigorously define the topological invariant for disordered interacting systems.Comment: final versio
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