Scanning Gate Imaging of quantum point contacts and the origin of the 0.7 Anomaly

Abstract

The origin of the anomalous transport feature appearing at conductance G \approx 0.7 x (2e2/h) in quasi-1D ballistic devices - the so-called 0.7 anomaly - represents a long standing puzzle. Several mechanisms were proposed to explain it, but a general consensus has not been achieved. Proposed explanations are based on quantum interference, Kondo effect, Wigner crystallization, and more. A key open issue is whether point defects that can occur in these low-dimensional devices are the physical cause behind this conductance anomaly. Here we adopt a scanning gate microscopy technique to map individual impurity positions in several quasi-1D constrictions and correlate these with conductance characteristics. Our data demonstrate that the 0.7 anomaly can be observed irrespective of the presence of localized defects, and we conclude that the 0.7 anomaly is a fundamental property of low-dimensional systems.

References in corpus (12)

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• Electron interferometer formed with a scanning probe tip and quantum point contact
• Imaging Electron Interferometer
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• Selective control of edge-channel trajectories by scanning gate microscopy
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Cited by in corpus (5)

• Ballistic one-dimensional holes with strong g-factor anisotropy in germanium
• Scanning gate microscopy of nonretracing electron-hole trajectories in a normal-superconductor junction
• Accurate characterization of tip-induced potential using electron interferometry
• Supercurrent modulation in InSb nanoflag-based Josephson junctions by scanning gate microscopy
• Signatures of Majorana bound states in scanning gate microscopy of hybrid nanowires