arXiv subjects

A. Donabidowicz

Publications and source records attributed to A. Donabidowicz.

4 recordsLinked to original sources

arXiv2009

Electron pair current through the correlated quantum dot

We study the charge current transmitted through the correlated quantum dot characterized by a finite magnitude of the Coulomb interaction |U|. At low temperatures the correlations can lead to appearance of the spin (for U>0) or charge (for U<0) Kondo states qualitatively affecting the transport properties. We explore an influence of the charge Kondo effect on the electron pair tunneling introducing the auxiliary two-component model which describes the fluctuations between empty and doubly occupied states of the quantum dot.

cond-mat.str-el↗

arXiv2008

Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes

Magnetic field applied to the quantum dot coupled between one metallic and one superconducting electrode can produce a similar effect as has been experimentally observed by Meservey, Tedrow and Fulde [Phys. Rev. Lett. 25, 1270 (1970)] for the planar normal metal -- superconductor junctions. We investigate the tunneling current and show that indeed the square root singularities of differential conductance exhibit the Zeeman splitting near the gap edge features V = +/- Delta/e. Since magnetic field affects also the in-gap states of quantum dot it furthermore imposes a hyperfine structure on the anomalous (subgap) Andreev current which has a crucial importance for a signature of the Kondo resonance.

cond-mat.supr-con↗

arXiv2007

Correlation effects in the transport through quantum dots

We study the charge and heat transport through the correlated quantum dot with a finite value of the charging energy U \neq \infty . The Kondo resonance appearing at temperatures below T_K is responsible for several qualitative changes of the electric and thermal transport. We show that under such conditions the semiclassical Mott relation between the thermopower and electric conductivity is violated. We also analyze the other transport properties where a finite charging energy U has a significant influence. They are considered here both, in the limit of small and for arbitrarily large values of the external voltage eV and/or temperature difference. In particular, we check validity of the Wiedemann-Franz law and the semiclassical Mott relation.

cond-mat.str-el↗

arXiv2006

The flow equation approach to the pairing instability problem

By means of the continuous unitary transformation similar to a general scheme of the Renormalization Group (RG) procedure we study the issue of symmetry breaking and pairing instability in the system of interacting fermions. Constructing a generalized version of the Bogoliubov transformation we show that formation of the fermion pairs and their superconductivity/superfluidity can appear at different temperatures. It is shown that strong quantum fluctuations can destroy the long-range order without breaking the fermion pairs which may still exist as incoherent and/or damped entities. Such unusual phase is characterized by a partial suppression of the density of states near the Fermi energy and by residual collective features like the sound-wave mode in the fermion pair spectrum.

cond-mat.supr-con↗