Effect of Rashba splitting on ultrafast carrier dynamics in BiTeI

Anna S. Ketterl, Beatrice Andres, Marco Polverigiani, Vladimir Voroshnin, Cornelius Gahl, Konstantin A. Kokh, Oleg E. Tereshchenko, Evgueni V. Chulkov, Alexander Shikin, Martin Weinelt

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Narrow-gap semiconductors with strong spin-orbit coupling such as bismuth tellurohalides have become popular candidates for spintronic applications. But driving spin-polarized photocurrents in these materials with circularly polarized light requires picosecond lifetimes of the photoexcited carriers and low spin-flip scattering rates. In search of these essential ingredients, we conducted an extensive study of the carrier dynamics on the Te-terminated surface of BiTeI, which exhibits a giant Rashba splitting of both surface and bulk states. We observe a complex interplay of surface and bulk dynamics after photoexcitation. Carriers are rapidly rearranged in momentum space by quasielastic phonon and defect scattering, while a phonon bottleneck leads to a slow equilibration between bulk electrons and lattice. The particular band dispersion opens an inelastic decay channel for hot carriers in the form of plasmon excitations, which are immanent to Rashba-split systems. These ultrafast scattering processes effectively redistribute excited carriers in momentum and energy space and thereby inhibit spin-polarized photocurrents.

Original languageEnglish
Article number085406
JournalPhysical Review B
Volume103
Issue number8
DOIs
Publication statusPublished - 3 Feb 2021

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