1 / 24

Thermal Enhancement of Interference Effects in Quantum Point Contacts

Thermal Enhancement of Interference Effects in Quantum Point Contacts. Adel Abbout, Gabriel Lemarié and Jean-Louis Pichard Phys. Rev. Lett. 106, 156810 (2011). IRAMIS/SPEC CEA Saclay Service de Physique de l’Etat Condensé, 91191 Gif Sur Yvette cedex, France.

quincy
Download Presentation

Thermal Enhancement of Interference Effects in Quantum Point Contacts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Thermal Enhancement of Interference Effects in Quantum Point Contacts Adel Abbout, Gabriel Lemarié and Jean-Louis Pichard Phys. Rev. Lett. 106, 156810 (2011) IRAMIS/SPEC CEA Saclay Service de Physique de l’Etat Condensé, 91191 Gif Sur Yvette cedex, France

  2. Electron Interferometer formed with a quantum point contact and another scatterer in a 2DEG

  3. Interferences in one dimension 1d model with 2 scatterers L Scatterers with a weakly energy dependent transmission

  4. Interferences with a resonance L

  5. 2d model:Resonant Level Model for a quantum point contact

  6. From the RLM model towards realistic contacts RLM model QPCs in a 2DEG

  7. SGM imaging Conductance of the QPC as a function of the tip position (Harvard, Stanford, Cambridge, Grenoble,…)Topinka et al., Physics Today (Dec. 2003) 2DEG , QPC AFM cantilever The charged tip creates a depletion region inside the 2deg which can be scanned around the nanostructure (qpc) Dg falls off with distance r from the QPC, exhibiting fringes spaced by lF/2

  8. QPC Model used in the numerical studyLong and smooth adiabatic contactSharp opening of the conduction channels + TIP (Square Lattice at low filling, t=1, EF=0.1)

  9. QPC biased at the beginning of thefirstplateau(Tip: V=1) T=0 T = 0.01 EF

  10. QPC biased at the beginning of thesecondplateau(Tip: V=-2) T=0 T =0.035 EF

  11. Resonant Level Model2 semi-infinite square lattices with a tip (potential v) on the right side coupled via a site of energy V0 and coupling terms -tc

  12. Self-energies describing the coupling to leadsexpressed in terms of surface elements of the lead GFsMethod of the mirror images for the lead GFs. Dyson equation for the tip • Transmission without tip ~ Lorentzian of width • Transmission with tip (Generalized Fisher-Lee formula) Narrow resonance:

  13. Expansion of the transmission T(E) when is small (Shot noise) Out of resonance: T0 < 1, 1/x Linear terms At resonance: T0=1; S0=0 1/x2 quadratic terms

  14. T=0 : Conductance • Out of resonance: • At resonance: Fringes spaced by (1/x decay) Almost no fringes (1/x2 decay)

  15. T > 0: Conductanceat resonance • 2 scales: • Temperature induced fringes: Thermal length: New scale:

  16. Rescaled Amplitude 1. Universal T-independent decay: 2. Maximum for Bottom to top: increasing temperature

  17. Numerical simulations and analytical resultsIncreasing temperature (top to bottom)

  18. The thermal enhancement can only be seen around the resonance

  19. RLM modelQPC ? • The expansion obtained in the RLM model can be extended to the QPC, if one takes the QPC staircase function instead of the RLM Lorentzian for T0(E). • The width of the energy interval where S0=T0(1-T0) is not negligible for the QPC plays the role of the of the RLM model for the QPC.

  20. Interference fringes obtained with a QPC and previous analytical results assuming the QPC transmission function Transmission ½ without tip, Redcurve: analyticalresults Black points: numerical simulations

  21. Peak to peak amplitude

  22. Similar scaling laws for the thermoelectric coefficients and the thermal conductance

  23. Summary

More Related