Münster 1999 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 9: Postersitzung I: TT-Teilchendetektoren (1-7), TT-Techniken (8-11), 2-D-Systeme (12-21), Meso- u. nanoskopische Strukturen (22-44), Niederdim. Spinsysteme (45-60), Tunneln u. Symmetrien (61-65), SQUID-Anwendungen (66-73), Massive HTSL, Bandleiter (74-96)

TT 9.34: Poster

Dienstag, 23. März 1999, 09:30–12:30, Z

Low temperature Kondo physics in metallic single-electron transistors — •F.K. Wilhelm^1,2, G. Zarand¹, and G.T. Zimanyi¹ — ¹University of California, Davis CA 95616, USA — ²Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe

We study the low temperature physics of a metallic single electron transistor in the strong tunneling regime at the degeneracy point. This system is equivalent to a highly anisotropic N_S=2 channel Kondo model, where N_S=2 is the electron spin degeneracy. This implies, that the low-T conductance is ∝ T^2/2+N_S. By a scaling analysis, we show, that as T→0, all microscopic realizations of this system flow into the N_S=2 fixed point. To be more specific, we can identify a crossover temperature T^∗ as follows: For T>T^∗ the physical properties of the model (conductance, capacitance) are indistinguishable from that of an N=N_S· M channel Kondo model, where M is the number of vertical modes in the lead, wheres for T<T^∗, the two-channel Kondo behavior is observed. For an initiallly completely random T-matrix and large M, T^∗ is extremely small, which justifies the assumptions in [1], whereas in the presence of a few initial correlations, the scenario in [2] is more likely. We examine several microscopic models for the barriers and their T-matrices with respect to this scaling behavior and compare our results to recent experiments [3].

[1] D.S. Golubev et al., Phys. Rev. B 56, 4730 (1997).

[2] K.A. Matveev, JETP 72, 892 (1991).

[3] Ph. Joyez et al., Phys. Rev. Lett. 79, 1349 (1997).