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Nat Commun. 2014 Jun 30;5:4290. doi: 10.1038/ncomms5290.

Wigner and Kondo physics in quantum point contacts revealed by scanning gate microscopy.

Author information

1
1] University Grenoble Alpes, F-38000 Grenoble, France [2] CNRS, Inst. NEEL, F-38042 Grenoble, France.
2
IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium.
3
CNRS, Laboratoire de Photonique et de Nanostructures, UPR20, F-91460 Marcoussis, France.
4
1] University Grenoble Alpes, F-38000 Grenoble, France [2] IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium.
5
1] University Grenoble Alpes, F-38000 Grenoble, France [2] CEA, INAC-SPSMS, F-38054 Grenoble, France.

Abstract

Quantum point contacts exhibit mysterious conductance anomalies in addition to well-known conductance plateaus at multiples of 2e(2)/h. These 0.7 and zero-bias anomalies have been intensively studied, but their microscopic origin in terms of many-body effects is still highly debated. Here we use the charged tip of a scanning gate microscope to tune in situ the electrostatic potential of the point contact. While sweeping the tip distance, we observe repetitive splittings of the zero-bias anomaly, correlated with simultaneous appearances of the 0.7 anomaly. We interpret this behaviour in terms of alternating equilibrium and non-equilibrium Kondo screenings of different spin states localized in the channel. These alternating Kondo effects point towards the presence of a Wigner crystal containing several charges with different parities. Indeed, simulations show that the electron density in the channel is low enough to reach one-dimensional Wigner crystallization over a size controlled by the tip position.

PMID:
24978440
DOI:
10.1038/ncomms5290
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