Charge rearrangement and screening in a quantum point contact.
Compressibility measurements are performed on a quantum point contact (QPC). Screening due to mobile charges in the QPC is measured quantitatively, using a second point contact. These measurements are performed from pinch-off through the opening of the first few modes in the QPC. While the measured signal closely matches a Thomas-Fermi-Poisson prediction, deviations from the classical behavior are apparent near the openings of the different modes. Density functional calculations attribute the deviations to a combination of a diverging density of states at the opening of each one-dimensional mode and exchange interaction, which is strongest for the first mode.
Department of Physics, Stanford University, Stanford, CA 94305, USA.
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Lüscher
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Moore
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Rejec
Yigal
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Meir
Hadas
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Shtrikman
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Goldhaber-Gordon