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We investigate transport through a mononuclear transition-metal complex with strong tunnel coupling to two electrodes. The ground state of this molecule is a singlet while the first excited state is a triplet. We show that a modulation of…

Strongly Correlated Electrons · Physics 2007-05-23 K. Kikoin , M. N. Kiselev , M. R. Wegewijs

We consider a triple quantum dot system in a triangular geometry with one of the dots connected to metallic leads. Using Wilson's numerical renormalization group method, we investigate quantum entanglement and its relation to the…

Strongly Correlated Electrons · Physics 2015-06-15 S. B. Tooski , A. Ramsak , R. Zitko , B. R. Bulka

We study an orbitally degenerate Kondo effect in a triangular triple quantum dot (TTQD), where the three dots are connected vertically with a single metallic lead through electron tunneling. Both spin and orbital degrees of freedom play an…

Mesoscale and Nanoscale Physics · Physics 2016-05-20 Mikito Koga , Masashige Matsumoto , Hiroaki Kusunose

Few-electron quantum dots are investigated in the regime of strong tunneling to the leads. Inelastic cotunneling is used to measure the two-electron singlet-triplet splitting above and below a magnetic field driven singlet-triplet…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 D. M. Zumbuhl , C. M. Marcus , M. P. Hanson , A. C. Gossard

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 the influence of spin-orbit coupling on the Kondo effects in carbon nanotube quantum dots, using the numerical renormalization group technique. A sufficiently large spin-orbit coupling is shown to destroy the SU(4) Kondo…

Strongly Correlated Electrons · Physics 2010-03-11 Martin R. Galpin , Frederic W. Jayatilaka , David E. Logan , Frithjof B. Anders

Transport properties of an interacting triple quantum dot system coupled to three leads in a triangular geometry has been studied in the Kondo regime. Applying mean-field finite-U slave boson and embedded cluster approximations to the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 E. Vernek , C. A. Busser , G. B. Martins , E. V. Anda , N. Sandler , S. E. Ulloa

The Kondo effect is a cornerstone in the study of strongly correlated fermions. The coherent exchange coupling of conduction electrons to local magnetic moments gives rise to a Kondo cloud that screens the impurity spin. Whereas complete…

Manipulation of the spin-states of a quantum dot by purely electrical means is a highly desirable property of fundamental importance for the development of spintronic devices such as spin-filters, spin-transistors and single-spin memory as…

Mesoscale and Nanoscale Physics · Physics 2008-10-20 J. R. Hauptmann , J. Paaske , P. E. Lindelof

We analyze here a model for single-electron charging in semiconductor quantum dots that includes the standard Anderson on-site repulsion (U) as well as the spin-exchange ($J_d$) that is inherently present among the electrons occupying the…

Condensed Matter · Physics 2009-10-22 Yi Wan , Philip Phillips , Qiming Li

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

Cotunneling transport through quantum dots weakly coupled to non-collinearly magnetized leads is analyzed theoretically by means of the real-time diagrammatic technique. The electric current, dot occupations, and dot spin are calculated in…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 Ireneusz Weymann , Jozef Barnas

We engineer a system of two strongly confined quantum dots to gain reproducible electrostatic control of the spin at zero magnetic field. Coupling the dots in a tight ring-shaped potential with two tunnel barriers, we demonstrate that an…

The Kondo-effect is a many-body phenomenon arising due to conduction electrons scattering off a localized spin. Coherent spin-flip scattering off such a quantum impurity correlates the conduction electrons and at low temperature this leads…

Strongly Correlated Electrons · Physics 2007-05-23 J. Paaske , A. Rosch , P. Woelfle , N. Mason , C. M. Marcus , J. Nygard

We investigated the peculiarities of non-equilibrium charge configurations in the system of two strongly coupled quantum dots (QDs) weakly connected to the reservoirs in the presence of Coulomb correlations. We revealed that total electron…

Mesoscale and Nanoscale Physics · Physics 2014-09-23 V. N. Mantsevich , N. S. Maslova , P. I. Arseyev

The physics of a junction composed of a normal metal, quantum dot and 2D topological insulator (in a quantum spin Hall state) is elucidated. It maifests a subtle combination of Kondo correlations and quantum spin Hall edge states moving on…

Strongly Correlated Electrons · Physics 2013-05-30 Igor Kuzmenko , Anatoly Golub , Yshai Avishai

We study the Kondo effect in a quantum dot which is coupled to ferromagnetic leads and analyse its properties as a function of the spin polarization of the leads. Based on a scaling approach we predict that for parallel alignment of the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 J. Martinek , Y. Utsumi , H. Imamura , J. Barnas , S. Maekawa , J. König , G. Schön

A low-temperature scanning tunneling microscope was employed to study the differential conductance in an atomic junction formed by an adsorbed Co atom on a Cu(100) surface and a copper-covered tip. A zero-bias anomaly (ZBA) reveals spin…

Mesoscale and Nanoscale Physics · Physics 2018-03-07 Deung-Jang Choi , Paula Abufager , Laurent Limot , Nicolas Lorente

A triangular triple quantum dot gives various Kondo effects, such as the emergence of an electric polarization accompanied by a complete compensation of spin degrees of freedom. The interplay of spin and charge of electrons in quantum dots…

Mesoscale and Nanoscale Physics · Physics 2016-06-03 Mikito Koga , Masashige Matsumoto , Hiroaki Kusunose

In a single state of a quantum dot the Kondo effect arises due to the spin-degeneracy, which is present if the dot is occupied with one electron (N = 1). The eigenstates of a carbon nanotube quantum dot possess an additional orbital…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 B. Babic , T. Kontos , C. Schoenenberger