The three-dimensional topological insulator Bi2Se3presents two cone-like dispersive topological surface states centered at the Î point. One of them is unoccupied in equilibrium conditions and located 1.8 eV above the other one lying close to the Fermi level. In this work we employ time- and angle-resolved photoemission spectroscopy with circularly polarized pump photons to selectively track the spin dynamics of the empty topological states. We observe that spin-polarized electrons flow along the topological cone and recombine towards the unpolarized bulk states on a timescale of few tens of femtoseconds. This provides direct evidence of the capability to trigger a spin current with circularly polarized light.
Ultrafast spin-polarized electron dynamics in the unoccupied topological surface state of Bi2Se3
Bugini, D.;Hedayat, H.;Zhou, X.;Manzoni, C.;Dallera, C.;Cerullo, G.;Carpene, E.
2017-01-01
Abstract
The three-dimensional topological insulator Bi2Se3presents two cone-like dispersive topological surface states centered at the Î point. One of them is unoccupied in equilibrium conditions and located 1.8 eV above the other one lying close to the Fermi level. In this work we employ time- and angle-resolved photoemission spectroscopy with circularly polarized pump photons to selectively track the spin dynamics of the empty topological states. We observe that spin-polarized electrons flow along the topological cone and recombine towards the unpolarized bulk states on a timescale of few tens of femtoseconds. This provides direct evidence of the capability to trigger a spin current with circularly polarized light.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
