Experimental measurement of the intrinsic excitonic wavefunction

An exciton, a two-body composite quasiparticle formed of an electron and hole, is a fundamental optical excitation in condensed-matter systems. Since its discovery nearly a century ago, a measurement of the excitonic wavefunction has remained beyond experimental reach. Here, we directly image the ex...

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Bibliographic Details
Published in:arXiv.org 2020-11
Main Authors: Man, Michael K L, Madéo, Julien, Sahoo, Chakradhar, Xie, Kaichen, Campbell, Marshall, Pareek, Vivek, Karmakar, Arka, E Laine Wong, Al-Mahboob, Abdullah, Chan, Nicholas S, Bacon, David R, Zhu, Xing, Abdelrasoul, Mohamed, Li, Xiaoquin, Heinz, Tony F, da Jornada, Felipe H, Cao, Ting, Dani, Keshav M
Format: Article
Language:English
Subjects:
Condensed matter physics
Conduction bands
Electrons
Elementary excitations
Excitons
Momentum
Valence band
Wave functions
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Summary:An exciton, a two-body composite quasiparticle formed of an electron and hole, is a fundamental optical excitation in condensed-matter systems. Since its discovery nearly a century ago, a measurement of the excitonic wavefunction has remained beyond experimental reach. Here, we directly image the excitonic wavefunction in reciprocal space by measuring the momentum distribution of electrons photoemitted from excitons in monolayer WSe2. By transforming to real space, we obtain a visual of the distribution of the electron around the hole in an exciton. Further, by also resolving the energy coordinate, we confirm the elusive theoretical prediction that the photoemitted electron exhibits an inverted energy-momentum dispersion relationship reflecting the valence band where the partner hole remains, rather than that of conduction-band states of the electron.
ISSN:2331-8422