28 research outputs found
Theory of a large thermoeffect in superconductors doped with magnetic impurities
We argue that parametrically strong enhancement of a thermoelectric current
can be observed in conventional superconductors doped by magnetic impurities.
This effect is caused by violation of the symmetry between electron-like and
hole-like excitations due to formation of subgap Andreev bound states in the
vicinity of magnetic impurities. We develop a quantitative theory of this
effect and demonstrate that it can be detected in modern experiments.Comment: 5 pages, 4 figure
Interplay between Josephson and Aharonov-Bohm effects in Andreev interferometers
Proximity induced quantum coherence of electrons in multi-terminal
voltage-driven hybrid normal-superconducting nanostructures may result in a
non-trivial interplay between topology-dependent Josephson and Aharonov-Bohm
effects. We elucidate a trade-off between stimulation of the voltage-dependent
Josephson current due to non-equilibrium effects and quantum dephasing of
quasiparticles causing reduction of both Josephson and Aharonov-Bohm currents.
We also predict phase-shifted quantum coherent oscillations of the induced
electrostatic potential as a function of the externally applied magnetic flux.
Our results may be employed for engineering superconducting nanocircuits with
controlled quantum properties
Crossed Andreev reflection at spin-active interfaces
With the aid of the quasiclassical Eilenberger formalism we develop a theory
of non-local electron transport across three-terminal ballistic
normal-superconducting-normal (NSN) devices with spin-active NS interfaces. The
phenomenon of crossed Andreev reflection (CAR) is known to play the key role in
such transport. We demonstrate that CAR is highly sensitive to electron spins
and yields a rich variety of properties of non-local conductance which we
describe non-perturbatively at arbitrary voltages, temperature, spin-dependent
interface transmissions and their polarizations. Our results can be applied to
multi-terminal hybrid structures with normal, ferromagnetic and half-metallic
electrodes and can be directly tested in future experiments.Comment: 11 pages, 7 figures; figures 6 and 7 are corrected; version published
in Phys. Rev.
Long-range Josephson effect controlled by temperature gradient and circuit topology
We demonstrate that the supercurrent can be strongly enhanced in cross-like
superconducting hybrid nanostructures (X-junctions) exposed to a temperature
gradient. At temperatures T exceeding the Thouless energy of our X-junction the
Josephson current decays algebraically with increasing T and can be further
enhanced by a proper choice of the circuit topology. At large values of the
temperature gradient the non-equilibrium contribution to the supercurrent may
become as large as the equilibrium one at low T. We also predict a variety of
transitions between 0- and -junction states controlled by the temperature
gradient as well as by the system geometry. Our predictions can be directly
verified in modern experiments.Comment: 10 pages, 5 figure
Long-range Josephson effect controlled by temperature gradient and circuit topology
We demonstrate that the supercurrent can be strongly enhanced in cross-like superconducting hybrid nanostructures (X-junctions) exposed to a temperature gradient. At temperatures T exceeding the Thouless energy of our X-junction, the Josephson current decays algebraically with increasing T and can be further enhanced by a proper choice of the circuit topology. At large values of the temperature gradient, the non-equilibrium contribution to the supercurrent may become as large as the equilibrium one at low T. We also predict a variety of transitions between 0- and π-junction states controlled by the temperature gradient as well as by the system geometry. Our predictions can be directly verified in modern experiments