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O: Fachverband Oberflächenphysik
O 71: Electronic Structure of Surfaces I
O 71.9: Vortrag
Mittwoch, 18. März 2020, 17:15–17:30, REC C 213
Double photoemission spectroscopy of SrTiO3(001) using a high-order harmonics light source — •Robin Kamrla1, Cheng-Tien Chiang1, Andreas Trützschler1, Michael Huth2, Frank Oliver Schumann2, and Wolf Widdra1,2 — 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany — 2Max Planck Institute of Microstructure Physics, Halle (Saale), Germany
Photoelectron spectroscopy (PES) has provided deep insights into the electronic
structure of solids. However, correlation effects can only be addressed indirectly. To observe such phenomena directly, double photoemission (DPE) spectroscopy is able to detect pairs of correlated photoelectrons that are emitted upon absorption of a single photon [1].
In this contribution we present PES and DPE data for SrTiO3(001), obtained by a laboratory high-order harmonic (HHG) light source at hν = 25.2 and 32.4 eV operating at MHz repetition rates. Well-ordered SrTiO3(001) surfaces have been prepared by annealing at 770 K in an oxygen atmosphere of 5· 10−6 mbar. PES confirms a TiO2 terminated surface and reveals a binding energy of the O2p state of 3.2 eV. In DPE we find an onset for emission of correlated photoelectrons at a pair binding energy of 7.5 eV, independent of the individual electron energies. The DPE data will be compared to data for NiO and CoO surfaces, as well as for Ag(001) [2], indicating the presence of a strong electron-electron interaction in SrTiO3.
[1] J. Berakdar et al., Phys. Rev. Lett. 81 (1998)
[2] A. Trützschler et al., Phys. Rev. Lett. 118 (2017)