Prof. Jörg Kröger: Quantum Physics at Surfaces

Ort : NW1 S1360
Beginn : 07. Mai 2019, 15:00 Uhr
Ende : 07. Mai 2019, 16:00 Uhr

J. Kröger
Institut für Physik, Technische Universität Ilmenau

Scanning tunnelling and atomic force microscopes are hard to avoid in contemporary quantum physics at surfaces and interfaces. The talk aims at giving an overview on the fascinating physics explored by these experimental tools.

For instance, buried cavities at Pb(111) surfaces act as resonators that vertically confine electrons between the vacuum-Pb and Pb-cavity interfaces giving rise to the well known quantum well states. Moreover, lateral confinement occurs due to electron reflection at the open boundary where the thin Pb film above the cavity recovers its bulk thickness [1,2].

Inelastic electron tunnelling spectroscopy unravels phonons of graphene on Ir(111). The spectroscopic signal is extraordinarily high in graphene wrinkles and samples intercalated by alkali metals. Calculations highlight the important role of the phonon density of states, the electrode-graphene hybridization, and the electron-phonon coupling in graphene [3,4].

As a third example photon emission from the tunnelling barrier will show that the spectroscopic line shape of single-molecule fluorescence light unveils the interplay between the localized tip-induced plasmon, the inelastic tunnelling electron, and the molecular exciton [5].

If time permits unpublished data on current-induced bond forces between two C60 molecules will be presented. These forces are relevant at chemical-bond distances between the molecules and reflect the non-equilibrium population of bonding and anti-bonding orbitals [6].

[1] M. Müller, N. Néel, S. Crampin, J. Kröger, Phys. Rev. Lett. 117, 136803 (2016)

[2] M. Müller, N. Néel, S. Crampin, J. Kröger, Phys. Rev. B 96, 205426 (2017)

[3] N. Néel, C. Steinke, T. O. Wehling, J. Kröger, Phys. Rev. B 95, 161410(R) (2017)

[4] J. Halle, N. Néel, M. Fonin, M. Brandbyge, J. Kröger, Nano Lett. 18, 5697 (2018)

[5] J. Kröger, B. Doppagne, F. Scheurer, G. Schull, Nano Lett. 18, 3407 (2018)

[6] J. Brand, S. Leitherer, N. R. Papior, N. Néel, Y. Lei, M. Brandbyge, J. Kröger, submitted