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Emergent photovoltage on SmB(6) surface upon bulk-gap evolution revealed by pump-and-probe photoemission spectroscopy

Recent studies suggest that an exemplary Kondo insulator SmB(6) belongs to a new class of topological insulators (TIs), in which non-trivial spin-polarized metallic states emerge on surface upon the formation of Kondo hybridization gap in the bulk. Remarkably, the bulk resistivity reaches more than...

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Detalles Bibliográficos
Autores principales: Ishida, Y., Otsu, T., Shimada, T., Okawa, M., Kobayashi, Y., Iga, F., Takabatake, Y., Shin, S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4313084/
https://www.ncbi.nlm.nih.gov/pubmed/25640966
http://dx.doi.org/10.1038/srep08160
Descripción
Sumario:Recent studies suggest that an exemplary Kondo insulator SmB(6) belongs to a new class of topological insulators (TIs), in which non-trivial spin-polarized metallic states emerge on surface upon the formation of Kondo hybridization gap in the bulk. Remarkably, the bulk resistivity reaches more than 20 Ω cm at 4 K, making SmB(6) a candidate for a so-called bulk-insulating TI. We here investigate optical-pulse responses of SmB(6) by pump-and-probe photoemission spectroscopy. Surface photovoltage effect is observed below ~90 K. This indicates that an optically-active band bending region develops beneath the novel metallic surface upon the bulk-gap evolution. The photovoltaic effect persists for >200 µs, which is long enough to be detected by electronics devices, and could be utilized for optical gating of the novel metallic surface.