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Two-stage Kondo effect in a four-electron artificial atom

G. Granger·M. A. Kastner·Iuliana Radu·M. P. Hanson·A. C. Gossard
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Abstract

An artificial atom with four electrons is driven through a singlet-triplet transition by varying the confining potential. In the triplet, a Kondo peak with a narrow dip at drain-source voltage V_ds=0 is observed. The low energy scale V_ds* characterizing the dip is consistent with predictions for the two-stage Kondo effect. The phenomenon is studied as a function of temperature T and magnetic field B, parallel to the two-dimensional electron gas. The low energy scales T* and B* are extracted from the behavior of the zero-bias conductance and are compared to the low energy scale V_ds* obtained from the differential conductance. Good agreement is found between kT* and |g|muB*, but eV_ds* is larger, perhaps because of nonequilibrium effects.

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G. Granger, M. A. Kastner, Iuliana Radu, M. P. Hanson, A. C. Gossard. 2005-07-20. Two-stage Kondo effect in a four-electron artificial atom. https://doi.org/10.1103/physrevb.72.165309

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