Attractive Dipolar Coupling between Stacked Exciton Fluids

Colin Hubert, Yifat Baruchi, Yotam Mazuz-Harpaz, Kobi Cohen, Klaus Biermann, Mikhail Lemeshko, Ken West, Loren Pfeiffer, Ronen Rapaport, Paulo Santos

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12 Scopus citations

Abstract

Dipolar coupling plays a fundamental role in the interaction between electrically or magnetically polarized species such as magnetic atoms and dipolar molecules in a gas or dipolar excitons in the solid state. Unlike Coulomb or contactlike interactions found in many atomic, molecular, and condensed-matter systems, this interaction is long-ranged and highly anisotropic, as it changes from repulsive to attractive depending on the relative positions and orientation of the dipoles. Because of this unique property, many exotic, symmetry-breaking collective states have been recently predicted for cold dipolar gases, but only a few have been experimentally detected and only in dilute atomic dipolar Bose-Einstein condensates. Here, we report on the first observation of attractive dipolar coupling between excitonic dipoles using a new design of stacked semiconductor bilayers. We show that the presence of a dipolar exciton fluid in one bilayer modifies the spatial distribution and increases the binding energy of excitonic dipoles in a vertically remote layer. The binding energy changes are explained using a many-body polaron model describing the deformation of the exciton cloud due to its interaction with a remote dipolar exciton. The surprising nonmonotonic dependence on the cloud density indicates the important role of dipolar correlations, which is unique to dense, strongly interacting dipolar solid-state systems. Our concept provides a route for the realization of dipolar lattices with strong anisotropic interactions in semiconductor systems, which open the way for the observation of theoretically predicted new and exotic collective phases, as well as for engineering and sensing their collective excitations.

Original languageAmerican English
Article number021026
JournalPhysical Review X
Volume9
Issue number2
DOIs
StatePublished - 8 May 2019

Bibliographical note

Funding Information:
The authors thank Stefan Fölsch and Maxim Khodas for fruitful discussions and comments on the manuscript. This research was made possible by the German-Israeli Foundation (GIF) Grant Agreement No. I-1277-303.10/2014 and the Austrian Science Fund (FWF), Project No. P29902-N27. We also acknowledge the support by the Israel Science Foundation, Grant No. 836/17. The work at Princeton University was funded by the Gordon and Betty Moore Foundation through EPiQS initiative Grant No. GBMF4420 and by NSF MRSEC Grant No. DMR-1420541.

Publisher Copyright:
© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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