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TT: Tiefe Temperaturen
TT 16: Korrelierte Elektronen: Quantenstörstellen, Kondo-Physik
TT 16.9: Talk
Tuesday, March 9, 2004, 18:45–19:00, H19
Finite-size effects in an ultrasmall Kondo quantum box — •Thomas Hand, Hans Kroha, and Hartmut Monien — Physikalisches Institut, Universität Bonn
We investigate the correlation effects induced by a Kondo impurity embedded in such a quantum box, using as a model a one-dimensional tight-binding band with a finite number of lattice sites which is coupled to an Anderson impurity. The model is solved by means of the density matrix renormalization group (DMRG) including the Lanczos method as well as the correction vector method. We examined systems with more than 500 sites and kept 2600 states. We define the Kondo temperature TK for the case of a discrete conduction electron density of states (level spacing Δ E). The strength of the correlations, indicated by the weight of the Kondo resonance, W, is determined by the local conduction density of states at the impurity site, x0. Hence, in addition to the even/odd effect predicted in [1], W depends both on the symmetry of the conduction electron wave function at the Fermi edge, Ψ0(x), and on the impurity position x0. We also investigate the crossover to the continuum limit.
[1] W. B. Thimm, J. Kroha, and J. v. Delft, Phys. Rev. Lett. 82, 2143 (1999).