Restricted and unrestricted Hartree-Fock calculations of conductance for a quantum point contact

Abstract

Very short quantum wires (quantum contacts) exhibit a conductance structure at a value of conductance close to $0.7\times 2e^2/h$. It is believed that the structure arises due to the electron-electron interaction, and it is also related to electron spin. However details of the mechanism of the structure are not quite clear. Previously we approached the problem within the restricted Hartree-Fock approximation. This calculation demonstrated a structure similar to that observed experimentally. In the present work we perform restricted and unrestricted Hartree-Fock calculations to analyze the validity of the approximations. We also consider dependence of the effect on the electron density in leads. The unrestricted Hartree-Fock method allows us to analyze trapping of the single electron within the contact. Such trapping would result in the Kondo model for the ``0.7 structure''. The present calculation confirms the spin-dependent bound state picture and does not confirm the Kondo model scenario.

arXiv comment6 pages, 9 figures

References in corpus (12)

• Possible Spin Polarization in a One-Dimensional Electron Gas
• The Anderson Model out of Equilibrium: Non-Crossing-Approximation Approach to Transport through a Quantum Dot
• The Low-Temperature Fate of the 0.7 Structure in a Point Contact: A Kondo-like Correlated State in an Open System
• Interaction Effects in a One-Dimensional Constriction
• Kondo model for the "0.7 anomaly" in transport through a quantum point contact
• Bias and temperature dependence of the 0.7 conductance anomaly in Quantum Point Contacts
• Many-body spin related phenomena in ultra-low-disorder quantum wires
• A Simple Formula for the Persistent Current in Disordered 1D Rings: Parity and Interaction Effects
• Ferromagnetic correlations in quasi-one-dimensional conducting channels
• Conductance anomalies in a one-dimensional quantum contact
• Possible mechanism of the fractional conductance quantization in a one-dimensional constriction
• Coulomb Blockade Resonances in Quantum Wires

Cited by in corpus (16)

• Spin-charge separation and localization in one-dimension
• Conductance of a quantum wire at low electron density
• What lurks below the last plateau: Experimental studies of the 0.7 x 2e^2/h conductance anomaly in one-dimensional systems
• Wigner and Kondo physics in quantum point contacts revealed by scanning gate microscopy
• Spin coupling in zigzag Wigner crystals
• Localization in an Inhomogeneous Quantum Wire
• Entanglement between static and flying qubits in quantum wires
• Wigner Crystallization in inhomogeneous one dimensional wires
• Residual conductance of correlated one-dimensional nanosystems: A numerical approach
• Conductance quantization in etched Si/SiGe quantum point contacts
• Magnetic Moment Formation in Quantum Point Contacts
• Thermoelectric Scanning Gate Interferometry on a Quantum Point Contact
• Shot noise reduction in quantum wires with "0.7 structure"
• A Scaling Approach for Interacting Quantum Wires -a Possible Explanation for the 0.7 Anomalous Conductance
• Many-body interactions in a quantum wire in the integer quantum Hall regime: suppression of exchange-enhanced g factor
• Entanglement and transport anomalies in nanowires