Excited-state band structure mapping

Physical Review X(submitted), (2021)

Excited-state band structure mapping

M. Puppin,C. W. Nicholson,C. Monney,Y. Deng,R. P. Xian,J. Feldl,S. Dong,A. Dominguez,H. Húbener,A. Rubio,M. Wolf,L. Rettig, R. Ernstorfer

Angle-resolved photoelectron spectroscopy is an extremely powerful probe of materials to access the occupied electronic structure with energy and momentum resolution. However, it remains blind to those dynamic states above the Fermi level that determine technologically relevant transport properties. In this work, we extend band structure mapping into the unoccupied states and across the entire Brillouin zone by using a state-of-the-art high repetition rate, extreme ultraviolet fem- tosecond light source to probe optically excited samples. The wide-ranging applicability and power of this approach are demonstrated by measurements on the 2D semiconductor WSe2, where the energy-momentum dispersion of valence and conduction bands are observed in a single experiment. This provides a direct momentum-resolved view not only on the complete out-of-equilibrium band gap but also on its renormalization induced by electron-hole interaction and screening. Our work establishes a new benchmark for measuring the band structure of materials, with direct access to the energy-momentum dispersion of the excited-state spectral function.

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Preprint - 21.9 MB
This work was funded by the Max-Planck-Gesellschaft, by the German Research Foundation (DFG) within the Emmy Noether program (Grant No. RE 3977/1), and grants FOR1700 (project E5), SPP2244 (project 443366970) and from the European Research Council, Grant Numbers ERC-2015-CoG-682843. M.P. acknowledge financial support by the Swiss National Science Foundation (SNSF) Grant No. CRSK-2 196756. C.W.N. and C.M. acknowledge financial support by the Swiss National Science Foundation (SNSF) Grant No. P00P2 170597. A.R. and H.H acknowledge financial support from the European Research Council (Grant ERC-2015-AdG-694097) and the Cluster of Excellence CUI:Advanced Imaging of Matter of the Deutsche Forschungsgemeinschaft (Grant EXC 2056 Project 390715994).

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