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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{|єd|,|U+єd|} 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).