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We investigate the effects of voltage induced spin-relaxation in a quantum dot in the Kondo regime. Using nonequilibrium perturbation theory, we determine the joint effect of self-energy and vertex corrections to the conduction electron…

Strongly Correlated Electrons · Physics 2007-05-23 J. Paaske , A. Rosch , J. Kroha , P. Wölfle

When individual quantum spins are placed in close proximity to conducting substrates, the localized spin is coupled to the nearby itinerant conduction electrons via Kondo exchange. In the strong coupling limit this can result in the Kondo…

Mesoscale and Nanoscale Physics · Physics 2014-11-04 F. Delgado , C. F. Hirjibehedin , J. Fernandez-Rossier

By means of a diagram technique for Hubbard operators we show the existence of a spin-dependent renormalization of the localized levels in an interacting region, e.g. quantum dot, modeled by the Anderson Hamiltonian with two conduction…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 J. Fransson , O. Eriksson , I. Sandalov

Using a laterally-fabricated quantum-dot (QD) spin-valve device, we experimentally study the Kondo effect in the electron transport through a semiconductor QD with an odd number of electrons (N). In a parallel magnetic configuration of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 K. Hamaya , M. Kitabatake , K. Shibata , M. Jung , M. Kawamura , K. Hirakawa , T. Machida , T. Taniyama , S. Ishida , Y. Arakawa

We study low-energy transport through a quantum dot coupled to one normal and two superconducting (SC) leads in a junction of Y-shape. In this geometry a crossover between Kondo dominated and Cooper-pairing dominated states occurs by tuning…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 Akira Oguri , Yoichi Tanaka , Johannes Bauer

We study the full counting statistics of electronic transport through a single-level quantum dot weakly coupled to two leads, with either one or both of them being ferromagnetic. The interplay of Coulomb interaction and finite spin…

Mesoscale and Nanoscale Physics · Physics 2009-06-05 Stephan Lindebaum , Daniel Urban , Jürgen König

We study the nonequilibrium spin current through a quantum dot consisting of two localized spin-1/2 coupled to two ferromagnetic insulators. The influence of an intra-dot magnetic field and exchange coupling, different dot-reservoir…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Olaf Strelcyk , Thomas Korb , Herbert Schoeller

We study a quantum dot connected to the bulk by single-mode junctions at almost perfect conductance. Although the average charge $e\langle N \rangle$ of the dot is not discrete, its spin remains quantized: $s=1/2$ or $s=0$, depending…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 L. I. Glazman , F. W. J. Hekking , A. I. Larkin

The linear and nonlinear transport through a multi-level lateral quantum dot connected to two leads is investigated using a generalized finite-$U$ slave-boson mean field approach. For a two-level quantum dot, our calculation demonstrates a…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Bing Dong , X. L. Lei

We investigate the effects induced by spin polarization in the contacts attached to a serial double quantum dot. The polarization generates effective magnetic fields and suppresses the Kondo effect in each dot. The super-exchange…

Mesoscale and Nanoscale Physics · Physics 2012-06-14 Rok Žitko , Jong Soo Lim , Rosa Lopez , Jan Martinek , Pascal Simon

We investigate a lateral semiconductor quantum dot with a large number of electrons in the limit of strong coupling to the leads. A Kondo effect is observed and can be tuned in a perpendicular magnetic field. This Kondo effect does not…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 C. Fuhner , U. F. Keyser , R. J. Haug , D. Reuter , A. D. Wieck

We study both the electrical and thermal transport near the heavy-fermion quantum critical point (QCP), identified with the breakdown of the Kondo effect as an orbital selective Mott transition. We show that the contribution to the…

Strongly Correlated Electrons · Physics 2015-05-13 K. -S. Kim , C. Pépin

This paper is devoted to a systematic exposure of the Kondo physics in quantum dots for which the low energy spin excitations consist of a few different spin multiplets $|S_{i}M_{i}>$. Under certain conditions (to be explained below) some…

Strongly Correlated Electrons · Physics 2007-05-23 Tetyana Kuzmenko , Konstantin Kikoin , Yshai Avishai

We study a symmetrical double quantum dot (DD) system with strong capacitive inter-dot coupling using renormalization group methods. The dots are attached to separate leads, and there can be a weak tunneling between them. In the regime…

Strongly Correlated Electrons · Physics 2009-11-07 L. Borda , G. Zarand , W. Hofstetter , B. I. Halperin , J. von Delft

We study the AC conductance and equilibrium current fluctuations of a Coulomb blockaded quantum dot. A relation between the equilibrium spectral function and the linear AC conductance is derived which is valid for frequencies well below the…

Strongly Correlated Electrons · Physics 2009-11-10 M. Sindel , W. Hofstetter , J. von Delft , M. Kindermann

We review the peculiarities of transport through a quantum dot caused by the spin transition in its ground state. Such transitions can be induced by a magnetic field. Tunneling of electrons between the dot and leads mixes the states…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 M. Pustilnik , L. I. Glazman , D. H. Cobden , L. P. Kouwenhoven

Motivated by the experimental evidence of the Nagaoka ferromagnetism in quantum dot systems by Dehollain et al [1], we search for possible confirmation of such kind of ferromagnetism by analyzing the spin-resolved transport properties of a…

Mesoscale and Nanoscale Physics · Physics 2024-10-04 Piotr Trocha , Emil Siuda , Ireneusz Weymann

We examine transport through a quantum dot coupled to three ferromagnetic leads in the regime of weak tunnel coupling. A finite source-drain voltage generates a nonequilibrium spin on the otherwise non-magnetic quantum dot. This spin…

Mesoscale and Nanoscale Physics · Physics 2007-09-28 Daniel Urban , Matthias Braun , Jürgen König

The spin-resolved thermoelectric transport properties of correlated nanoscale junctions, consisting of a quantum dot/molecule asymmetrically coupled to external ferromagnetic contacts, are studied theoretically in the far-from-equilibrium…

Mesoscale and Nanoscale Physics · Physics 2023-07-21 Anand Manaparambil , Ireneusz Weymann

We investigate the effect of spatial symmetries on phase coherent electronic transport through chaotic quantum dots. For systems which have a spatial symmetry that interchanges the source and drain leads, we find in the framework of random…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Victor A. Gopar , Stefan Rotter , Henning Schomerus