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Ultrafast melting and recovery of collective order in the excitonic insulator Ta2NiSe5

Bretscher, HM and Andrich, P and Telang, P and Singh, A and Harnagea, L and Sood, AK and Rao, A (2021) Ultrafast melting and recovery of collective order in the excitonic insulator Ta2NiSe5. In: Nature Communications, 12 (1).

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Official URL: https://doi.org/10.1038/s41467-021-21929-3


The layered chalcogenide Ta2NiSe5 has been proposed to host an excitonic condensate in its ground state, a phase that could offer a unique platform to study and manipulate many-body states at room temperature. However, identifying the dominant microscopic contribution to the observed spontaneous symmetry breaking remains challenging, perpetuating the debate over the ground state properties. Here, using broadband ultrafast spectroscopy we investigate the out-of-equilibrium dynamics of Ta2NiSe5 and demonstrate that the transient reflectivity in the near-infrared range is connected to the system�s low-energy physics. We track the status of the ordered phase using this optical signature, establishing that high-fluence photoexcitations can suppress this order. From the sub-50 fs quenching timescale and the behaviour of the photoinduced coherent phonon modes, we conclude that electronic correlations provide a decisive contribution to the excitonic order formation. Our results pave the way towards the ultrafast control of an exciton condensate at room temperature. © 2021, The Author(s).

Item Type: Journal Article
Publication: Nature Communications
Publisher: Nature Research
Additional Information: The copyright for this article belongs to Nature Research
Keywords: article; infrared radiation; melting point; phonon; physics; room temperature; spectroscopy
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 30 Mar 2021 06:45
Last Modified: 30 Mar 2021 06:46
URI: http://eprints.iisc.ac.in/id/eprint/68565

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