1 / 24

BDT between Au leads

BDT between Au leads. Víctor García Suárez. Outline 1) Experiment 2) Previous calculations 3) Electronic and transport properties 4) Other experiments and simulations. 1) Experiment. Experiment. First transport measurement across a molecular junction

corin
Download Presentation

BDT between Au leads

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. BDT between Au leads Víctor García Suárez

  2. Outline 1) Experiment 2) Previous calculations 3) Electronic and transport properties 4) Other experiments and simulations

  3. 1) Experiment

  4. Experiment First transport measurement across a molecular junction Mechanicaly controllable break junction with gold molecules adsorbed on the gold wire surface Conductance ~ 10-4 G0 (up to 0.1 G0, Tsutsui et al. Appl. Phys. Lett. 89, 163111 (2006)) Reed et al., Science 278, 252 (1997) I-V characteristics

  5. 2) Previous calculations

  6. First theoretical calculation BDT molecule connected to ideal electrodes Qualitative agreement between theory and experiment Current and conductace Di Ventra et al., Phys. Rev. Lett. 84, 979 (2000)

  7. Full ab-initio calculation BDT molecule between Au(111) electrodes Zero bias and out of equlibrium LUMO Transmission Xue and Ratner , Phys. Rev. B 68, 115406 (2003) HOMO

  8. Other calculations Other coupling configurations Results did not agree with experiments Stokbro et al., Computational Materials Science 27, 151 (2003) Transmission Correlated electron transport Quantitative agreement for the conductance but not for the I-V Delaney and Greer, Phys. Rev. Lett. 93, 36805 (2004)

  9. 3) Electronic and transport properties

  10. First approximation to the transport properties p* - Two-level system Each level represents a sulphur level; both levels interact across the central part of the molecule S S p Transmission obtained by changing the level coupling Match to the Ab-initio HOMO

  11. Smeagol results BDT between Au(001) leads SZ basis set; 9 atoms per lead; 93 atoms in total; slightlty stretched Transmission and density of states Phys. Rev. B 80, 085426 (2009)

  12. Effect of stretching and I-V BDT between Au(001) under stretching and bias voltage Under strain the junction becomes asymmetric; qualitative I-V agreement Phys. Stat. Sol. 7, 2443 (2007) Effect of stretching Effect of bias

  13. Example of calculation BDT between Au(001) leads with 9 atoms per slice ABAB stacking; coupling on the hollow position (square); distance of 1.9 Å from the surface; periodic boundary conditions along the perpendicular directions; 93 atoms in total

  14. Leads calculation %block kgrid_Monkhorst_Pack 1 0 0 0.0 0 1 0 0.0 0 0 100 0.0 %endblock kgrid_Monkhorst_Pack xc.functional GGA xc.authors PBE MeshCutoff 200. Ry MaxSCFIterations 10000 DM.MixingWeight 0.1 DM.NumberPulay 8 DM.MixSCF1 T DM.Tolerance 1.d-4 SolutionMethod diagon ElectronicTemperature 150 K SaveElectrostaticPotential T BuildSuperCell T InitTransport T BulkTransport T BulkLead LR DM.UseSaveDM T SystemName Au SystemLabel Au NumberOfAtoms 18 NumberOfSpecies 1 %block ChemicalSpeciesLabel 1 79 Au %endblock ChemicalSpeciesLabel %block PAO.Basis Au 1 n=6 0 1 5.0 %endblock PAO.Basis %block Ps.lmax Au 1 %endblock Ps.lmax LatticeConstant 1.00 Ang %block LatticeVectors 6.120 6.120 0.000 6.120 -6.120 0.000 0.000 0.000 4.080 %endblock LatticeVectors AtomicCoordinatesFormat Ang %block AtomicCoordinatesAndAtomicSpecies 0.00 0.00 0.00 1 Au 1 ... 0.00 6.12 2.04 1 Au 18 %endblock AtomicCoordinatesAndAtomicSpecies

  15. Extended molecule calculation SystemName Au.em SystemLabel Au.em NumberOfAtoms 93 NumberOfSpecies 4 %block ChemicalSpeciesLabel 1 1 H 2 6 C 3 16 S 4 79 Au %endblock ChemicalSpeciesLabel PAO.EnergyShift 0.02 Ry %block PAO.BasisSizes H SZ C SZ S SZ %endblock PAO.BasisSizes %block PAO.Basis Au 1 n=6 0 1 5.0 %endblock PAO.Basis %block Ps.lmax Au 1 %endblock Ps.lmax LatticeConstant 1.00 Ang %block LatticeVectors 6.120 6.120 0.000 6.120 -6.120 0.000 0.000 0.000 27.042 %endblock LatticeVectors ... EMTransport T BuildSuperCell T InitTransport T NEnergReal 500 NEnergImCircle 50 NEnergImLine 30 NPoles 10 VInitial 0.d0 eV VFinal 0.d0 eV NIVPoints 0 Delta 2.d-4 EnergLowestBound -8.d0 Ry NSlices 1 AtomLeftVCte 18 AtomRightVCte 76 TrCoefficients T NTransmPoints 800 InitTransmRange -10.5d0 eV FinalTransmRange -0.5d0 eV PeriodicTransp T UseLeadsGF F HartreeLeadsLeft -6.44d0 Ang HartreeLeadsRight 16.52d0 Ang HartreeLeadsBottom -16.36013222 eV DM.UseSaveDM T

  16. Dependence on the lateral size of the electrodes Size of the electrodes a a function of the number of atoms per layer: From 4 to 25 atoms per layer (Au 001)

  17. Dependence on the basis set Type of basis set on the electrodes and molecule: From SZ in the molecule or leads to DZP in all atoms

  18. Dependence on the number of lateral k-points Number of k-points along the perpendicular directions From the G point to 24 k-points

  19. 5) Other experiments and simulations

  20. 2D conductance histograms of OPE molecules Number of measurements as a function of length and conductance An elliptical zone that moves down as a function of length and another circular zone for very stretched configurations Wandlosky et al. Unpublished (yet)

  21. Simulation of BDT with corrected levels (SAINT) BDT coupled with different atomic configurations and tilt angles Results that agree qualitatively and quantitatively with experiments BDT between Au(111) surfaces Rigid shift of levels

  22. Conductance as a function of angle and coupling atom I Hollow and top configurations Hollow-hollow (not very probable) Hollow-top

  23. Conductance as a function of angle and coupling atom II Top configuration Top-top Conductance values

  24. Fin

More Related