The 2-Channel Kondo Model: II. CFT Calculation of Non-equilibrium Conductance through a Nanoconstriction Containing 2-Channel Kondo Impurities
✍ Scribed by Jan von Delft; A.W.W. Ludwig; Vinay Ambegaokar
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 568 KB
- Volume
- 273
- Category
- Article
- ISSN
- 0003-4916
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✦ Synopsis
Recent experiments by Ralph and Buhrman on zero-bias anomalies in quenched Cu nanoconstrictions (reviewed in a preceding paper) are in accord with the assumption that the interaction between electrons and nearly degenerate two-level systems in the constriction can be described, for sufficiently small voltages and temperatures (V, T<T K ), by the 2-channel Kondo (2CK) model. Motivated by these experiments, we introduce a generalization of the 2CK model, which we call the nanoconstriction 2-channel Kondo model (NTKM), that takes into account the complications arising from the non-equilibrium electron distribution in the nanoconstriction. We calculate the conductance G(V, T) of the constriction in the weakly non-equilibrium regime of V, T< <T K by combining concepts from Hershfield's Y-operator formulation of non-equilibrium problems and Affleck and Ludwig's exact conformal field theory (CFT) solution of the 2CK problem (CFT technicalities will be discussed in a subsequent paper). Finally, we extract from the conductance a universal scaling curve 1(v) and compare it with experiment. Combining our results with those of Hettler, Kroha, and Hershfield, we conclude that the NTKM achieves quantitative agreement with the experimental scaling data. 1999 Academic Press Contents. I. Introduction. II. The nanoconstriction Non-magnetic Kondo Model. A. Free Hamiltonian H 0 . B. The free density matrix \ 0 . C. The free current through the nanoconstriction. D. The nanoconstriction 2CK interaction. E. Poor man's scaling equations unaffected by V. III. Outline of