Relaxation Dynamics of Photoexcited Charge Carriers at the Bi(111) Surface

Abstract

Bi possesses intriguing properties due to its large spin-orbit coupling, e.g. as a constituent of topological insulators. While its electronic structure and the dynamics of electron-phonon coupling have been studied in the past, photo-induced charge carriers have not been observed in the early phases of their respective relaxation pathways. Using two-photon photoemission (2PPE) we follow the de-excitation pathway of electrons along the unoccupied band structure and into a bulk hole pocket. Two decay channels are found, one of which involves an Auger process. In the hole pocket, the electrons undergo an energetic stabilization and recombine with the corresponding holes with an inverse rate of 2.5~ps. Our results contribute to the understanding of the charge carrier relaxation processes immediately upon photo-excitation, particularly along the $\Gamma T$-line where the electron dynamics have not been probed with time-resolved 2PPE so far.

arXiv comment8 pages, 5 figures

References in corpus (5)

• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Strong spin-orbit splitting on Bi surfaces
• Coherent Phonon Coupling to Individual Bloch States in Photoexcited Bismuth
• Giant Anisotropy of Spin-Orbit Splitting at the Bismuth Surface
• Unoccupied electronic band structure of the semi-metallic Bi(111) surface probed with two-photon photoemission

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