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TT: Tiefe Temperaturen

TT 8: Mesoskopische Systeme I

TT 8.3: Talk

Tuesday, March 12, 2002, 10:15–10:30, H20

Dynamics of a tunneling magnetic impurity: Kondo effect induced incoherence — •Laszlo Borda¹ and Gergely Zarand² — ¹LS von Delft, Sektion Physik und CeNS, Ludwig-Maximilians-Universität,Theresienstr. 37, 80333 München — ²Lyman Physics laboratory, Harvard University, Cambridge MA 02145

We study how the formation of the Kondo compensation cloud influences the dynamical properties of a magnetic impurity that tunnels between two positions in a metal. The Kondo effect dynamically generates a strong tunneling impurity-conduction electron coupling, changes the temperature dependence of the tunneling rate, and may ultimately result in the destruction of the coherent motion of the particle at zero temperature. We find an interesting two-channel Kondo fixed point as well for a vanishing overlap between the electronic states that screen the magnetic impurity. We propose a number of systems where the predicted features could be observed.