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Photo-excited Dynamics in the Excitonic Insulator Ta2NiSe5
- Publication Year :
- 2018
-
Abstract
- The excitonic insulator is an intriguing correlated electron phase formed of condensed excitons. A promising candidate is the small band gap semiconductor Ta2NiSe5. Here we investigate the quasiparticle and coherent phonon dynamics in Ta2NiSe5 in a time resolved pump probe experiment. Using the models originally developed by Kabanov et al. for superconductors, we show that the material's intrinsic gap can be described as almost temperature independent for temperatures up to about 250 K to 275 K. This behavior supports the existence of the excitonic insulator state in Ta2NiSe5. The onset of an additional temperature dependent component to the gap above these temperatures suggests that the material is located in the BEC-BCS crossover regime. Furthermore, we show that this state is very stable against strong photoexcitation, which reveals that the free charge carriers are unable to effectively screen the attractive Coulomb interaction between electrons and holes, likely due to the quasi one-dimensional structure of Ta2NiSe5.<br />27 pages, 8 figures
- Subjects :
- Physics
Condensed Matter::Quantum Gases
Strongly Correlated Electrons (cond-mat.str-el)
Condensed matter physics
business.industry
Band gap
Phonon
Exciton
FOS: Physical sciences
02 engineering and technology
021001 nanoscience & nanotechnology
Condensed Matter Physics
Condensed Matter::Mesoscopic Systems and Quantum Hall Effect
01 natural sciences
Photoexcitation
Condensed Matter - Strongly Correlated Electrons
Semiconductor
Excited state
0103 physical sciences
Quasiparticle
General Materials Science
Charge carrier
010306 general physics
0210 nano-technology
business
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....e73e440fc939f61a49ce549873c1ee5f