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The Kondo effect and the Fano-Kondo effect are important phenomena that have been observed in quantum dots (QDs). We theoretically investigate the transport properties of a coupled QD system in order to study the possibility of detecting a…

Strongly Correlated Electrons · Physics 2013-05-09 Tetsufumi Tanamoto , Yu-xi Liu , Xuedong Hu , Franco Nori

We investigate the equilibrium and out-of-equilibrium Kondo effects in a single-level interacting quantum dot connected to two ferromagnetic leads. Within the non-crossing approximation, we calculate the total density of states (DOS), the…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Bing Dong , H. L. Cui , S. Y. Liu , X. L. Lei

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 report the observation of Kondo physics in a spin- 3/2 hole quantum dot. The dot is formed close to pinch-off in a hole quantum wire defined in an undoped AlGaAs/GaAs heterostructure. We clearly observe two distinctive hallmarks of…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 O. Klochan , A. P. Micolich , A. R. Hamilton , K. Trunov , D. Reuter , A. D. Wieck

We study two tunnel-coupled quantum dots each with a spin 1/2 and attached to leads in the Coulomb blockade regime. We study the interplay between Kondo correlations and the singlet-triplet exchange splitting $K$ between the two spins. We…

Strongly Correlated Electrons · Physics 2009-11-07 Vitaly N. Golovach , Daniel Loss

We study competition between the Kondo effect and superconductivity in a single self-assembled InAs quantum dot contacted with Al lateral electrodes. Due to Kondo enhancement of Andreev reflections the zero-bias anomaly develops sidepeaks,…

Mesoscale and Nanoscale Physics · Physics 2009-09-29 Christo Buizert , Akira Oiwa , Kenji Shibata , Kazuhiro Hirakawa , Seigo Tarucha

We analyze the equilibrium transport properties of underscreened Kondo effect in the case of a two-level quantum dot coupled to ferromagnetic leads. Using the numerical renormalization group (NRG) method, we have determined the gate voltage…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Ireneusz Weymann , Laszlo Borda

Superconductivity in van der Waals materials, such as NbSe$_{2}$ and TaS$_{2}$, is fundamentally novel due to the effects of dimensionality, crystal symmetries, and strong spin-orbit coupling. In this work we perform tunnel spectroscopy on…

In a tunneling experiment across a quantum dot it is possible to change the coupling between the dot and the contacts at will, by properly tuning the trasparency of the barriers and the temperature. Gate voltages allow for changes of the…

Strongly Correlated Electrons · Physics 2009-11-10 Domenico Giuliano , Adele Naddeo , Arturo Tagliacozzo

It has been suggested that a zero-bias conductance peak in quantum wires signifies the presence of Kondo spin-correlations, which might also relate to an intriguing 1D spin-effect known as the 0.7 structure. These zero-bias anomalies (ZBA)…

Mesoscale and Nanoscale Physics · Physics 2009-04-17 T. -M. Chen , A. C. Graham , M. Pepper , I. Farrer , D. A. Ritchie

We report on a comprehensive study of spin-1/2 Kondo effect in a strongly-coupled quantum dot realized in a high-quality InAs nanowire. The nanowire quantum dot is relatively symmetrically coupled to its two leads, so the Kondo effect…

Nontrivial topological superconductivity has received enormous research attentions due to its potential for diverse applications in topological quantum computing. The intrinsic issue concerning the correlation between a topological…

We study the spin-resolved transport through single-level quantum dots strongly coupled to ferromagnetic leads in the Kondo regime, with a focus on contact and material asymmetry-related effects. By using the numerical renormalization group…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 K. P. Wojcik , I. Weymann , J. Barnas

We report a strong Kondo effect (Kondo temperature ~ 4K) at high magnetic field in a selective area growth semiconductor quantum dot. The Kondo effect is ascribed to a singlet-triplet transition in the ground state of the dot. At the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 W. G. van der Wiel , S. De Franceschi , J. M. Elzerman , S. Tarucha , L. P. Kouwenhoven , J. Motohisa , F. Nakajima , T. Fukui

We measure the non-dissipative supercurrent in a single InAs self-assembled quantum dot (QD) coupled to superconducting leads. The QD occupation is both tuned by a back-gate electrode and lateral side-gate. The geometry of the side-gate…

Mesoscale and Nanoscale Physics · Physics 2010-09-30 Y. Kanai , R. S. Deacon , A. Oiwa , K. Yoshida , K. Shibata , K. Hirakawa , S. Tarucha

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

The transport properties of a double quantum-dot device with one of the dots coupled to perfect conductors are analyzed using the numerical renormalization group technique and slave-boson mean-field theory. The coupling between the dots…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. S. Cornaglia , D. R. Grempel

Kondo correlations are responsible for the emergence of a zero-bias peak in the low temperature differential conductance of Coulomb blockaded quantum dots. In the presence of a global SU(2)$\otimes$SU(2) symmetry, which can be realized in…

The demand for low-power devices is on the rise as semiconductor engineering approaches the quantum limit and quantum computing continues to advance. Two-dimensional (2D) superconductors, thanks to their rich physical properties, hold…

The Kondo effect and superconductivity are both prime examples of many-body phenomena. Here we report transport measurements on a carbon nanotube quantum dot coupled to superconducting leads that show a delicate interplay between both…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 M. R. Buitelaar , T. Nussbaumer , C. Schoenenberger