Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: TR: Nanoelectronics I: Quantum Dots, Wires, Point Contacts 1

TT 29.7: Vortrag

Donnerstag, 25. März 2010, 11:00–11:15, H19

Crossover between the Kondo effect for quantum dots and the 0.7 conductance anomaly for quantum point contacts — •Jan Heyder, Florian Bauer, and Jan von Delft — Ludwig Maximilians Universitaet , Muenchen

It has been conjectured that the 0.7 conductance anomaly for transport through a quantum point contact (QPC) is closely related to the Kondo effect for transport through a quantum dot (QD) [1,2,3]. To study the relation between these two effects explicitly, we consider a 1-D quantum wire modeled by a tight-binding chain with short-ranged Coulomb interactions and a prescribed onsite potential, whose shape can be varied to mimick the smooth crossover from a double-barrier potential (QD geometry) to a single barrier potential (QPC geometry) as the bottom of the central valley is raised until the central valley disappears completely. We use the functional renormalization group to calculate the conductance, local density and local magnetization at zero temperature as a function of magnetic field, Coulomb interaction and potential shape. Our results reveal both striking similarities and striking differences between the parameter-dependencies of the 0.7 anomaly and the Kondo effect.

[1] Y. Meir, K. Hirose, N.S. Wingreen, Phys. Rev. Lett.,89, 196802 (2002).

[2] K. Hirose, Y. Meir, N. S. Wingreen, Phys. Rev.Lett.,90, 026804 (2003).

[3] T. Rejec, Y. Meir, Nature, 442, 900 (2006).