Charge Rearrangement and Screening in a Quantum Point Contact
S. Lüscher,1 L. S. Moore,1 T. Rejec,2 Yigal Meir,2 Hadas Shtrikman,3 and D. Goldhaber-Gordon1
1Department of Physics, Stanford University, Stanford, California 94305, USA
2Department of Physics, Ben Gurion University of the Negev, Beersheva, Israel
3Submicron Center, Weizmann Institute of Science, Rehovot, Israel
(Received 20 April 2006; published 11 May 2007)
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.
©2007 The American Physical Society
URL: http://link.aps.org/abstract/PRL/v98/e196805
doi:10.1103/PhysRevLett.98.196805
PACS: 73.21.Hb, 73.23.-b, 73.43.Fj, 73.61.Ey
Additional Information
Full Text: PDF
From PRL (you may need a
subscription for that) PDF
For more information on reference linking in this journal, see Reference Sections and Reference Linking in Abstracts.
Auxiliary Material (EPAPS)
- K. J. Thomas et al., Phys. Rev. Lett. 77, 135 (1996).
- R. de Picciotto et al., Phys. Rev. Lett. 92, 036805 (2004).
- C.-K. Wang et al., Phys. Rev. B 57, 4552 (1998). [ISI]
- B. Spivak and F. Zhou, Phys. Rev. B 61, 16 730 (2000).
- H. Bruus et al., Physica (Amsterdam) 10E, 97 (2001). [Inspec] [ISI]
- K. A. Matveev, Phys. Rev. B 70, 245319 (2004).
- Y. Meir et al., Phys. Rev. Lett. 89, 196802 (2002).
- K. Hirose et al., Phys. Rev. Lett. 90, 026804 (2003). [ISI]
- S. M. Cronenwett et al., Phys. Rev. Lett. 88, 226805 (2002).
- J. Eisenstein et al., Phys. Rev. Lett. 68, 674 (1992).
- S. Shapira et al., Phys. Rev. Lett. 77, 3181 (1996).
- S. Ilani et al., Nature (London) 427, 328 (2004).
- M. Field et al., Phys. Rev. Lett. 70, 1311 (1993).
- D. Sprinzak et al., Phys. Rev. Lett. 88, 176805 (2002). [ISI]
- J. M. Elzerman et al., Appl. Phys. Lett. 84, 4617 (2004).
- I. M. Castleton et al., Physica (Amsterdam) 249B, 157 (1998). [Inspec]
- M. Stopa, Phys. Rev. B 54, 13 767 (1996).
-
The simulation solves Schrödinger and Poisson equations in the growth
direction at each point on a grid in the plane of the 2DEG. Then it
calculates the density self-consistently using a Thomas-Fermi
approximation.
-
Pinch-off in the simulation is defined as the point where the
conduction band edge is equal to the Fermi energy exactly at the saddle
point.
- T. Rejec and Yigal Meir, Nature (London) 442, 900 (2006).
-
See EPAPS Document No. E-PRLTAO-98-033719 for details of DFT
calculations on the compressibility of electrons in a quantum point
contact, and implications for future experiments. For more information
on EPAPS, see http://www.aip.org/pubservs/epaps.html. [EPAPS]
-
The exclusion of exchange and correlation affects the density far away
from the QPC. To partly compensate for this effect we shifted the
Hartree curve so that it matches the DFT result far beyond pinch-off.
- S. Ilani et al., Nature Phys. 2, 687 (2006).