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Damian Krychowski

Publications and source records attributed to Damian Krychowski.

3 recordsLinked to original sources

Fractional shot noise of an SU(N) Kondo system

We consider transport through a multi-level interacting quantum dot (N-QD) in Kondo regime. Using the Kotliar-Ruckentein slave boson approach (SBMFA) for N-level Anderson model we define effectively noninteracting quasiparticles of the SU(N) Kondo system ($N=2,3,4,5,6$). Kondo resonance transmission coefficients determine linear noise describing quasiparticle partitioning. To discuss nonlinear conductance, susceptibilities and shot noise in the strong coupling regime, we apply Fermi liquid theory with parameters expressed by susceptibilities of pseudofermions determined within SBMFA. Nonlinear shot noise is dominated by two-quasiparticle scattering. However, we demonstrate that for occupation regions distant from the electron-hole symmetry point, the role of three-body correlations must be revealed.

cond-mat.str-el

Kondo effect of cobalt adatom on zigzag graphene nanoribbon

Based on ab-initio calculations we discuss Kondo effect due to Co adatom on graphene zigzag nanoribbon. Co atom located at hollow site behaves as spin S = 1/2 impurity with dxz and dyz orbitals contributing to magnetic moment. Dynamical correlations are analyzed with the use of complementary approximations: mean field slave boson approach, noncrossing approximation and equation of motion method. The impact of interplay between spin and orbital degrees of freedom together with the effect of peculiarities of electronic and magnetic structure of nanoribbon on many-body resonances is examined.

cond-mat.mes-hall

Spin polarized current and shot noise in carbon nanotube quantum dot in the Kondo regime

Using nonequilibrium Green functions and several complementary many-body approximations we calculate shot noise and spin dependent conductance in carbon nanotube semiconducting quantum dot in spin-orbital Kondo regime. We point out on the possibility of reaching giant values of tunnel magnetoresistance in this range and discuss a prospect of its gate control. We also analyze the influence of symmetry breaking perturbations on the shot noise with special emphasis on spin dependent effects. The gate and bias dependencies of noise Fano factors influenced by magnetic field, polarization of electrodes and spin-flip processes are presented.

cond-mat.mes-hall