Ultrafast Electronic Band Gap Control in an Excitonic Insulator.
Phys Rev Lett
; 119(8): 086401, 2017 Aug 25.
Article
em En
| MEDLINE
| ID: mdl-28952776
ABSTRACT
We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta_{2}NiSe_{5} investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of F_{C}=0.2 mJ cm^{-2}, the band gap narrows transiently, while it is enhanced above F_{C}. Hartree-Fock calculations reveal that this effect can be explained by the presence of the low-temperature excitonic insulator phase of Ta_{2}NiSe_{5}, whose order parameter is connected to the gap size. This work demonstrates the ability to manipulate the band gap of Ta_{2}NiSe_{5} with light on the femtosecond time scale.
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01-internacional
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MEDLINE
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En
Ano de publicação:
2017
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Article