Momentum-Resolved Spin Dynamics of Bulk and Surface Excited States in the Topological InsulatorBi2Se3
| Autor: | Emma Springate, Sarnjeet S. Dhesi, Federico Cilento, Fulvio Parmigiani, Hubert Ebert, Marco Grioni, Jan Minár, Cephise Cacho, Marco Battiato, Y. Liu, Alberto Crepaldi, Karsten Held, M. C. Richter, K. Hricovini, Ph. Bugnon, Michele Zacchigna, Helmuth Berger, Jürgen Braun, O. Heckmann |
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| Rok vydání: | 2015 |
| Předmět: |
Physics
Spintronics Spin polarization Condensed matter physics Band gap General Physics and Astronomy Position and momentum space Spin engineering 02 engineering and technology Spin structure 021001 nanoscience & nanotechnology 01 natural sciences Topological insulator Excited state 0103 physical sciences Condensed Matter::Strongly Correlated Electrons 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review Letters. 114 |
| ISSN: | 1079-7114 0031-9007 |
| Popis: | The prospect of optically inducing and controlling a spin-polarized current in spintronic devices has generated wide interest in the out-of-equilibrium electronic and spin structure of topological insulators. In this Letter we show that only measuring the spin intensity signal over several orders of magnitude by spin-, time-, and angle-resolved photoemission spectroscopy can provide a comprehensive description of the optically excited electronic states in Bi2Se3. Our experiments reveal the existence of a surface resonance state in the second bulk band gap that is benchmarked by fully relativistic ab initio spin- resolved photoemission calculations. We propose that the newly reported state plays a major role in the ultrafast dynamics of the system, acting as a bottleneck for the interaction between the topologically protected surface state and the bulk conduction band. In fact, the spin- polarization dynamics in momentum space show that these states display macroscopically different temperatures and, more importantly, different cooling rates over several picoseconds. |
| Databáze: | OpenAIRE |
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