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Shot Noise and conductance spectroscopy on a single molecule junction

Shot Noise and conductance spectroscopy on a single molecule junction. Oren Tal Michael Krieger, Rik Hortensius , Bas Leerink Robert Thijssen, Darko Djukic and Jan van Ruitenbeek Leiden University,Netherlands Capri Spring School 2007.

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Shot Noise and conductance spectroscopy on a single molecule junction

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  1. Shot Noise and conductance spectroscopy on a single molecule junction Oren Tal Michael Krieger, Rik Hortensius, Bas Leerink Robert Thijssen, Darko Djukic and Jan van Ruitenbeek Leiden University,Netherlands Capri Spring School 2007

  2. Inelastic Electron Tunneling Spectroscopy Typically low conductance ~10-5G0 Point Contact Spectroscopy Typically high conductance ~1G0 H2 C2H2 Djukic et al. Phys. Rev. B (R). 71 (2005), 161402 Thygesen et al. Phys. Rev. Lett. 94 (2005), 036807 Stipe et al. Rev. Sci. Inst.70 (1999), 137 Electron-Vibration Interaction

  3. Step up Step down Conductance curves of different molecular junctions

  4. “step up” to “step down” shape transition as a function of conductance

  5. Low Transmission High Transmission Step size and direction in conductance curves L. de la Vega, A. Martín-Rodero, N. Agraït, and A. Levy Yeyati, PRB 73, 075428 (2006) (M. Paulsson et al. PRB 72, 201101R (2005) similar 0.5 transition)

  6. Deviation from a single channel model Single channel model: transition between “step up” to “step down” at In our experiment: transition between “step up” to “step down” at Do we have more then a single transmission channel for a Pt-H2O -Pt junction? Shot Noise measurements

  7. τ1 … τi Shot noise in point contacts

  8. At the main transmission channel has The transition between to occurs above Shot noise in Pt+H2O single molecule junction 6

  9. Conclusions Point contact spectroscopy : The effect of electron - vibration interactions on the differential conductance is inverted at a certain conductance. Shot noise measurements: More than a single transmission channel through the Pt-H2O-Pt junction Using the combination of point contact spectroscopy and shot noise measurements the apparent deviation from the relevant models could be resolved. Open question: what is the role of transmission channel mixing due to electron – vibration interactions?

  10. Acknowledgments Prof. Jan van Ruitenbeek Michael Krieger Rik Hortensius Bas Leerink Robert Thijssen Darko Djukic Christian Martin Sander Otte Ruud van Egmond Bert Crama

  11. Point Contact Spectroscopy Typically high transmission probability Inelastic Electron Tunneling Spectroscopy Typically low transmission probability dI/dV dI/dV V 0V V 0V E E e eV e eV R k Electron-Phonon Interaction

  12. Spectrum Analyser PC Lock-in 1000 1000 I-V S1 100 100 S2 battery cryostat dipstick 100M Faraday cage Shot noise in point contacts

  13. At about G=0.5G0 the main transmission channel has The transition between to occurs above Shot noise in Pt+H2O single molecule junction 6

  14. “ Elastic” and inelastic contributions J. K. Viljan et al. PRB 72, 245415 (2005) 6

  15. Conductance histograms: Pt

  16. Conductance histograms: Pt+H2O >at lower bias voltages lower peaks are more pronounced.

  17. Conductance traces >Pt-H2O-Pt configurations with higher conductance then 1G0 (?)

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