Selective Probing of Photoinduced Charge and Spin Dynamics in the Bulk and Surface of a Topological Insulator
Abstract
Topological insulators possess completely different spin-orbit coupled bulk and surface electronic spectra that are each predicted to exhibit exotic responses to light. Here we report time-resolved fundamental and second harmonic optical pump-probe measurements on the topological insulator Bi_2Se_3 to independently measure its photoinduced charge and spin dynamics with bulk and surface selectivity. Our results show that a transient net spin density can be optically induced in both the bulk and surface, which may drive spin transport in topological insulators. By utilizing a novel rotational anisotropy analysis we are able to separately resolve the spin depolarization, intraband cooling, and interband recombination processes following photoexcitation, which reveal that spin and charge degrees of freedom relax on very different time scales owing to strong spin-orbit coupling.
Additional Information
© 2011 American Physical Society. Received 30 March 2011. Revised 1 June 2011. Published 10 August 2011. We thank Darius Torchinsky, Yihua Wang, and Stefan Kehrein for helpful discussions. This work is supported by DOE Grant No. DE-FG02-08ER46521.Attached Files
Published - PhysRevLett.107.077401.pdf
Supplemental Material - ARR_EPAPS_TR_SHG_6-1-2011.pdf
Supplemental Material - ARR_EPAPS_TR_SHG_6-1-2011.tex.txt
Supplemental Material - Fits.ai
Supplemental Material - Pizzas.ai
Supplemental Material - setup.ai
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Additional details
- Eprint ID
- 48614
- Resolver ID
- CaltechAUTHORS:20140815-110459643
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2014-08-22Created from EPrint's datestamp field
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2021-11-10Created from EPrint's last_modified field