FisMat2017 - Submission - View

Abstract's title: Ultrafast spin-current and spin-accumulation in topological insulators investigated by time- and angle-resolved photoemission spectroscopy
Submitting author: Davide Bugini
Affiliation: Politecnico di Milano
Affiliation Address: Piazza Leonardo da Vinci 32 I-20133 Milano
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Hamoon Hedayat (Dipartimento di Fisica, Politecnico di Milano), Fabio Boschini (Dipartimento di Fisica, Politecnico di Milano& Department of Physics and Astronomy, University of British Columbia, Vancouver), Hemian Yi (National Lab for Superconductivity, Institute of Physics, Chinese Academy of Science, Beijing), Chaoyu Chen (National Lab for Superconductivity, Institute of Physics, Chinese Academy of Science, Beijing), Xingjiang Zhou (National Lab for Superconductivity, Institute of Physics, Chinese Academy of Science, Beijing), Cristian Manzoni (CNR-IFN, Dipartimento di Fisica, Politecnico di Milano), Claudia Dallera (Dipartimento di Fisica, Politecnico di Milano), Giulio Cerullo (Dipartimento di Fisica, Politecnico di Milano), Ettore Carpene (CNR-IFN, Dipartimento di Fisica, Politecnico di Milano)
Abstract

In the last decade the interest in the possibility to control and manipulate the spin of the electron for a new generation of faster devices triggered the scientific community on the investigation of materials presenting a spin-order. In this framework, topological insulators (TIs) represent a hot-topic because of the in-plane spin-polarized surface states (TSS) arising within the bulk insulating energy gap[1,2]. The inhibition of the spin-flip events[3-5] and the control of the spin polarization using ultrashort light pulses[6-8] open new scenarios in the use of this class of materials for future opto-spintronic devices.

Using time- and angle-resolved photoemission spectroscopy (TR-ARPES) on the SbxBi(2−x)SeyTe(3−y) class we studied the response of spin-polarized electrons to ultrashort circularly-polarized pulses.

Here, we report for the first time the experimental evidence of a direct coupling between light and empty topological surface states (ESS) and the establishment of a flow of spin-polarized electrons in k-space i.e. a photon-induced spin-current. In addition, our data suggest an accumulation of spin-polarized electrons in the conduction band of TIs due to the spin-dependent decay channels.

 

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