Year: 2017
Type: article
Abstract: We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$ investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of ${F}_{C}=0.2\text{ }\text{ }\mathrm{mJ}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$, 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 ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$, whose order parameter is connected to the gap size. This work demonstrates the ability to manipulate the band gap of ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$ with light on the femtosecond time scale.
Source: Physical Review Letters
Institutions: Fritz Haber Institute of the Max Planck Society, University of Potsdam, University of Fribourg, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nagoya University, Okayama University, Max Planck Institute for Solid State Research, The University of Tokyo, Waseda University, University of Zurich
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,750
OpenAlex ID: W2513086999