Electrostatic potential shape of gate defined quantum point contacts

Abstract

Quantum point contacts (QPC) are fundamental building blocks of nanoelectronic circuits. For their emission dynamics as well as for interaction effects such as the 0.7-anomaly the details of the electrostatic potential are important, but the precise potential shapes are usually unknown. Here, we measure the one-dimensional subband spacings of various QPCs as a function of their conductance and compare our findings with models of lateral parabolic versus hard wall confinement. We find that a gate-defined QPC near pinch-off is compatible with the parabolic saddle point scenario. However, as the number of populated subbands is increased Coulomb screening flattens the potential bottom and a description in terms of a finite hard wall potential becomes more realistic.

arXiv comment7+2 pager, 7 figures, v2: published version (minor changes)

References in corpus (11)

• Interaction Effects in a One-Dimensional Constriction
• Magnetic impurity formation in quantum point contacts
• What lurks below the last plateau: Experimental studies of the 0.7 x 2e^2/h conductance anomaly in one-dimensional systems
• Transport Properties of Clean Quantum Point Contacts
• The influence of device geometry on many-body effects in quantum point contacts: Signatures of the 0.7 anomaly, exchange and Kondo
• On the relation between the 0.7-anomaly and the Kondo effect: Geometric Crossover between a Quantum Point Contact and a Kondo Quantum Dot
• Extreme sensitivity of the spin-splitting and 0.7 anomaly to confining potential in one-dimensional nanoelectronic devices
• Magneto-electrical subbands of freely suspended quantum point contacts
• Analysis of the temperature-dependent quantum point contact conductance in view of the metal-insulator transition in two dimensions
• Tracking the energies of one-dimensional subband edges in quantum point contacts using dc conductance measurements
• Field effect induced mesoscopic devices in depleted two dimensional electron systems

Cited by in corpus (5)

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• Microwave Sensing of Andreev Bound States in a Gate-Defined Superconducting Quantum Point Contact
• Signature of spin-resolved quantum point contact in p-type trilayer WSe${}_2$ van der Waals heterostructure
• Coherent Electron Optics with Ballistically Coupled Quantum Point Contacts
• Clean quantum point contacts in an InAs quantum well grown on a lattice-mismatched InP substrate