228 research outputs found
Quasi-one-dimensional system as a high-temperature superconductor
It is well-known that quasi-one-dimensional superconductors suffer from the
pairing fluctuations that significantly reduce the superconducting temperature
or even completely suppress any coherent behavior. Here we demonstrate that a
coupling to a robust pair condensate changes the situation dramatically. In
this case the quasi-one-dimensional system can be a high temperature
superconductor governed by the proximity to the Lifshitz transition at which
the Fermi level approaches the lower edge of the single-particle spectrum.Comment: 5 pages, 1 figur
Competitive 0 and {\pi} states in S/F multilayers: multimode approach
We have investigated the critical temperature behavior in periodic
superconductor/ ferromagnet (S/F) multilayers as a function of the
ferromagnetic layer thickness and the interface transparency. The
critical temperature exhibits a damped oscillatory behavior in these
systems due to an exchange field in the ferromagnetic material. In this work we
have performed calculations using the self-consistent multimode approach,
which is considered to be exact solving method. Using this approach we have
derived the conditions of 0 or state realization in periodic S/F
multilayers. Moreover, we have presented the comparison between the single-mode
and multimode approaches and established the limits of applicability of the
single-mode approximation, frequently used by experimentalists
Spatially-resolved probing of a non-equilibrium superconductor
Spatially resolved relaxation of non-equilibrium quasiparticles in a
superconductor at ultra-low temperatures was experimentally studied. It was
found that the quasiparticle injection through a tunnel junction results in
modification of the shape of I-V characteristic of a remote `detector'
junction. The effect depends on temperature, injection current and proximity to
the injector. The phenomena can be understood in terms of creation of
quasiparticle charge and energy disequilibrium characterized by two different
length scales m and
m. The findings are in good agreement with existing phenomenological
models, while more elaborated microscopic theory is mandatory for detailed
quantitative comparison with experiment. The results are of fundamental
importance for understanding electron transport phenomena in various
nanoelectronic circuits.Comment: 7 pages, 5 figure
Reentrant superconductivity in proximity to a topological insulator
In the following paper we investigate the critical temperature behavior
in the two-dimensional S/TI (S denotes superconductor and TI - topological
insulator) junction with a proximity induced in-plane helical magnetization in
the TI surface. The calculations of are performed using the general
self-consistent approach based on the Usadel equations in Matsubara Green's
functions technique. We show that the presence of the helical magnetization
leads to the nonmonotonic behavior of the critical temperature as a function of
the topological insulator layer thickness.Comment: submitted to Physical Review
Heat transport and electron cooling in ballistic normal-metal/spin-filter/superconductor junctions
Selected papers from the sixth Moscow International Symposium on Magnetism (MISM-2014).-- arXiv:1407.1977v2We investigate electron cooling based on a clean normal-metal/spin-filter/superconductor junction. Due to the suppression of the Andreev reflection by the spin-filter effect, the cooling power of the system is found to be extremely higher than that for conventional normal-metal/nonmagnetic-insulator/superconductor coolers. Therefore we can extract large amount of heat from normal metals. Our results strongly indicate the practical usefulness of the spin-filter effect for cooling detectors, sensors, and quantum bits.This work was supported by the Topological Quantum Phenomena (No. 23103520) KAKENHI on Innovative Areas, a Grant-in-Aid for Scientific Research (No. 25286046) from MEXT of Japan, the JSPS Institutional Program for Young Researcher Overseas Visits, the European Union Seventh Framework Programme (FP7/2007-2013) under Grant agreement “INFERNOS” no. 308850, the Spanish Ministry of Economy and Competitiveness under Project FIS2011-28851-C02-02, and the CSIC and the European Social Fund under JAE-Predoc programPeer Reviewe
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