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Journal Article

Giant Exciton Mott Density in Anatase TiO2

MPS-Authors
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Rubio,  A.
Theory Group, Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society;
Departamento Física de Materiales, Universidad del País Vasco;
Center for Computational Quantum Physics, The Flatiron Institute;

Fulltext (public)

PhysRevLett.125.116403.pdf
(Publisher version), 419KB

Supplementary Material (public)

MottDensity_SM.pdf
(Supplementary material), 2MB

Citation

Baldini, E., Palmieri, T., Dominguez, A., Rubio, A., & Chergui, M. (2020). Giant Exciton Mott Density in Anatase TiO2. Physical Review Letters, 125(11): 116403. doi:10.1103/PhysRevLett.125.116403.


Cite as: http://hdl.handle.net/21.11116/0000-0007-0DFD-F
Abstract
Elucidating the carrier density at which strongly bound excitons dissociate into a plasma of uncorrelated electron-hole pairs is a central topic in the many-body physics of semiconductors. However, there is a lack of information on the high-density response of excitons absorbing in the near-to-mid ultraviolet, due to the absence of suitable experimental probes in this elusive spectral range. Here, we present a unique combination of many-body perturbation theory and state-of-the-art ultrafast broadband ultraviolet spectroscopy to unveil the interplay between the ultraviolet-absorbing two-dimensional excitons of anatase TiO2 and a sea of electron-hole pairs. We discover that the critical density for the exciton Mott transition in this material is the highest ever reported in semiconductors. These results deepen our knowledge of the exciton Mott transition and pave the route toward the investigation of the exciton phase diagram in a variety of wide-gap insulators.