Mikhail S. Kalenkov

Low-temperature magnetic penetration depth in d-wave superconductors: Zero-energy bound state and impurity effects

We report a theoretical study on the deviations of the Meissner penetration depth

Nonlocal Andreev reflection at high transmissions

\lambda(T)

Josephson current in ballistic heterostructures with spin-active interfaces

from its London value in d-wave superconductors at low temperatures. The difference arises from low-energy surface Andreev bound states. The temperature dependent penetration depth is shown to go through a minimum at the temperature

Theory of a Large Thermoelectric Effect in Superconductors Doped with Magnetic Impurities

T_{m0}\sim \sqrt{\xi_0/\lambda_0}T_c

Crossed Andreev reflection and charge imbalance in diffusive normal-superconducting-normal structures.

if the broadening of the bound states is small. The minimum will straighten out when the broadening reaches

Triplet superconductivity in a ferromagnetic vortex.

T_{m0}

Josephson current and Andreev states in superconductor-half metal-superconductor heterostructures

. The impurity scattering sets up the low-temperature anomalies of the penetration depth and destroys them when the mean free path is not sufficiently large. A phase transition to a state with spontaneous surface supercurrent is investigated and its critical temperature determined in the absence of a subdominant channel activated at low temperatures near the surface. Nonlinear corrections from Andreev low-energy bound states to the penetration length are obtained and shown, on account of their broadening, to be small in the Meissner state of strong type II superconductors.

Crossed Andreev reflection at spin-active interfaces

We analyze non-local effects in electron transport across three-terminal normal-superconducting-normal (NSN) structures. Subgap electrons entering S-electrode from one N-metal may form Cooper pairs with their counterparts penetrating from another N-metal. This phenomenon of crossed Andreev reflection -- combined with normal scattering at SN interfaces -- yields two different contributions to non-local conductance which we evaluate non-perturbatively at arbitrary interface transmissions. Both these contributions reach their maximum values at fully transmitting interfaces and demonstrate interesting features which can be tested in future experiments.

Enhancement of thermoelectric effect in diffusive superconducting bilayers with magnetic interfaces

We develop a general microscopic theory of dc Josephson effect in hybrid superconductor\char21{}normal-metal\char21{}superconductor structures with ballistic electrodes and spin-active normal-metal\char21{}superconductor (NS) interfaces. We establish a direct relation between the spectrum of Andreev levels and the Josephson current which contains complete information about nontrivial interplay between Andreev reflection and spin-dependent interface scattering. The system exhibits a rich structure of properties sensitive to spin-dependent barrier transmissions, spin-mixing angles, relative magnetization orientation of interfaces, and the kinematic phase of scattered electrons. We analyze the current-phase relations and identify the conditions for the presence of a

Electron-hole imbalance and large thermoelectric effect in superconducting hybrids with spin-active interfaces

\ensuremath{\pi}