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Vodolazov D.Y.,RAS Institute for Physics of Microstructures
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The structure and energy of saddle point (SP) states in a two-dimensional (2D) superconducting film of finite width w with transport current I are found in the framework of the Ginzburg-Landau model. We show that very near the depairing current I dep, a SP state with a vortex does not exist; it transforms to a 2D nucleus state, which is a finite region with partially suppressed order parameter. It is also shown that for slightly lower currents the contribution of the vortex core energy is important for a SP state with a vortex and it cannot be neglected for I 0.6I dep. It is demonstrated that in a film with local current concentration near a bend, the energy of the SP state may be much smaller than that in the straight film, and this favors the effect of fluctuations in such samples. © 2012 American Physical Society. Source


Vodolazov D.Yu.,RAS Institute for Physics of Microstructures
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

We find the relation between the energy of the absorbed photon and the threshold current at which the resistive state appears in the current-carrying superconducting film with probability about unity. In our calculations we use the modified hot-spot model, which assumes a different strength of suppression of the superconducting order parameter in the finite area of the film around the place where the photon is absorbed. To find the threshold current we solve the Ginzburg-Landau equation for the superconducting order parameter, which automatically includes the current continuity equation and it allows us to consider the back effect of current redistribution near the hot spot on the stability of the superconducting state. We find quantitative agreement with recent experiments, where we use the single fitting parameter which describes what part of the energy of the photon goes for the local destruction of the superconductivity in the film. © 2014 American Physical Society. Source


Silaev M.A.,RAS Institute for Physics of Microstructures
Physical Review Letters | Year: 2012

We show that the vortex dynamics in Fermi superfluids at ultralow temperatures is governed by the local heating of the vortex cores creating the heat flux carried by nonequilibrium quasiparticles emitted by moving vortices. This mechanism provides a universal zero temperature limit of dissipation in Fermi superfluids. For the typical experimental conditions realized by the turbulent motion of He3-B, the temperature of the vortex cores is estimated to be of the order 0.2T c. The dispersion of Kelvin waves is derived, and the heat flow generated by Kelvin cascade is shown to have a value close to that experimentally observed. © 2012 American Physical Society. Source


Vodolazov D.Y.,RAS Institute for Physics of Microstructures
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

In the framework of the Ginzburg-Landau model, it is shown that narrow superconducting films with width w3-8ξ(T) [ξ(T) is a temperature-dependent coherence length] exhibit unusual transport properties. In the absence of bulk pinning, its critical current Ic nonmonotonically depends on perpendicular magnetic field H and has one minima (dip) and one maxima (peak) at some magnetic fields. At currents IIc(H), the finite magnetoresistance R(H) of such a sample due to thermoactivated vortex hopping via edge barriers also shows both local maxima (peak) and minima (dip) nearly at the same magnetic fields. In narrower films, such an effect is absent due to absence of the vortices and in wider films the effect is weaker due to increased vortex-vortex interaction. The finite length of the film produces additional periodic variation in both Ic(H) and R(H) because of discrete changes in the number of the vortices, which is superimposed on the above-mentioned nonmonotonic dependence. The obtained results are directly related to many experiments on narrow superconducting films/bridges where such nonmonotonic dependencies Ic(H) and R(H) were observed. © 2013 American Physical Society. Source


Silaev M.A.,RAS Institute for Physics of Microstructures
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We show that a periodic lattice of Abrikosov vortices in the type-II superconductor can support fermionic states with zero energy. Zero modes appear at the intersection of electronic Bloch bands with the Fermi level. In a chiral px+ipy wave superconductor the spectrum contains Majorana states at the center of an effective Brillouin zone. The Bloch bands formed by the overlapping vortex core states can transmit energy flow across the lattice. The hallmark of zero modes in electronic heat conductivity is discussed. © 2013 American Physical Society. Source

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