Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 34: Correlated Electrons - Quantum Impurities, Kondo Physics

TT 34.1: Talk

Wednesday, March 9, 2005, 09:45–10:00, TU H104

Frequency-dependent transport through a quantum dot in the Kondo regime — •Michael Sindel¹, Walter Hofstetter², Jan von Delft¹, and Markus Kindermann³ — ¹Physics Department and Center for NanoScience, LMU München, 80333 München — ²Institut für Theoretische Physik A, RWTH Aachen, 52056 Aachen — ³Department of Physics, Massachusetts Institute of Technology, Cambridge MA 02139, USA

Motivated by experiments of Kogan et al. [1] we study the AC conductance and equilibrium current fluctuations of a Coulomb blockaded quantum dot in the Kondo regime. To this end we apply the nonperturbative numerical renormalization group method in combination with the Kubo formalism [2] suitable for the nonperturbative calculation of finite-frequency transport properties. For frequencies smaller than the charge excitation energy min{|є_d|,|U+є_d|} we derive a formula for the frequency dependent current by extending [3]. This formula enables us to relate the spectral function with the linear AC conductance and the frequency-dependent equilibrium current fluctuations, respectively. We demonstrate that AC transport provides a new route to measuring the equilibrium spectral density (a key signature of Kondo physics) which so far has defied direct experimental observation.
A. Kogan, S. Amasha, and M.A. Kastner, Science 304, 1293 (2004).
W. Izumida, O. Sakai, and Y. Shimizu, J. Phys. Soc. Jpn. 66, 717 (1997).
A.-P. Jauho, N.S. Wingreen and Y. Meir, Phys. Rev. B 50, 5528 (1994).