Dresden 2017 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 42: Metallic Nanowires on Semiconductor Surfaces (jointly with O)
DS 42.4: Vortrag
Donnerstag, 23. März 2017, 15:45–16:00, WIL C107
Ultrafast Peierls Transition in In/Si(111) Nanowires Probed by trARPES — •C. W. Nicholson1, A. Lücke2, M. Puppin1, L. Rettig1, R. Ernstorfer1, W. Gero Schmidt2, and M. Wolf1 — 1Fritz-Haber-Institut, Berlin — 2Universität Paderborn
Quasi-1D metals on semiconducting substrates, of which In/Si(111) is one of the most interesting and intensively studied systems, promise not only novel 1D physics, but also control over electronic properties and dimensionality. In/Si(111) undergoes a structural transition from a (4x1) to an (8x2) unit cell at around 120 K, concomitant with a metal-to-insulator transition. A recent combined DFT and Raman study [1] points strongly to a Peierls-like scenario, whereby a combination of shear and rotary distortions leads to the opening of band gaps at specific points in the band structure.
Here we investigate the momentum resolved changes of the electronic structure during the ultrafast photoinduced Peierls transition using high-harmonic-driven trARPES with 50 fs time resolution. Starting from the (8x2) phase, we track the evolution of states both above and below the Fermi level following pulsed excitation and observe the transition from (8x2) to (4x1) phases on a 500 fs time scale. By comparison to complementary DFT calculations we analyse the contributions from the expected shear and rotary distortions to the transient electronic band structure. The observation of coherent phonon oscillations at 2.4 THz provides further insights into the many-body interactions in the system.
[1] E. Jeckelmann et al. Phys. Rev. B, 93, 241407(R) (2016)