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Title: Emergence of excitonic superfluid at topological-insulator surfaces

Abstract

Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature, and exciton condensates can be realized at much higher temperature than condensates of atoms because of strong Coulomb binding and small mass. Signatures of exciton condensation have been reported in double quantum wells, microcavities, graphene, and transition metal dichalcogenides. Nonetheless, transport of exciton condensates is not yet understood and it is unclear whether an exciton condensate is a superfluid or an insulating electronic crystal. Topological insulators (TIs) with massless particles and unique spin textures have been theoretically predicted as a promising platform for achieving exciton condensation. Here we report experimental evidence of excitonic superfluid phase on the surface of three-dimensional (3D) TIs. We unambiguously confirmed that electrons and holes are paired into charge neutral bound states by the electric field independent photocurrent distributions. And we observed a millimetre-long transport distance of these excitons up to 40 K, which strongly suggests dissipationless propagation. The robust macroscopic quantum states achieved with simple device architecture and broadband photoexcitation at relatively high temperature are expected to find novel applications in quantum computations and spintronics.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1546695
Report Number(s):
arXiv:1810.10653
Journal ID: ISSN 9999-0017; ark:/13030/qt1zs8s5n3
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
arXiv.org Repository
Additional Journal Information:
Journal Volume: 2018; Journal ID: ISSN 9999-0017
Publisher:
Cornell University
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Hou, Yasen, Wang, Rui, Xiao, Rui, McClintock, Luke, Travaglini, Henry Clark, Francia, John P, Fetsch, Harry, Erten, Onur, Savrasov, Sergey Y, Wang, Baigeng, Rossi, Antonio, Vishik, Inna, Rotenberg, Eli, and Yu, Dong. Emergence of excitonic superfluid at topological-insulator surfaces. United States: N. p., 2018. Web.
Hou, Yasen, Wang, Rui, Xiao, Rui, McClintock, Luke, Travaglini, Henry Clark, Francia, John P, Fetsch, Harry, Erten, Onur, Savrasov, Sergey Y, Wang, Baigeng, Rossi, Antonio, Vishik, Inna, Rotenberg, Eli, & Yu, Dong. Emergence of excitonic superfluid at topological-insulator surfaces. United States.
Hou, Yasen, Wang, Rui, Xiao, Rui, McClintock, Luke, Travaglini, Henry Clark, Francia, John P, Fetsch, Harry, Erten, Onur, Savrasov, Sergey Y, Wang, Baigeng, Rossi, Antonio, Vishik, Inna, Rotenberg, Eli, and Yu, Dong. Wed . "Emergence of excitonic superfluid at topological-insulator surfaces". United States.
@article{osti_1546695,
title = {Emergence of excitonic superfluid at topological-insulator surfaces},
author = {Hou, Yasen and Wang, Rui and Xiao, Rui and McClintock, Luke and Travaglini, Henry Clark and Francia, John P and Fetsch, Harry and Erten, Onur and Savrasov, Sergey Y and Wang, Baigeng and Rossi, Antonio and Vishik, Inna and Rotenberg, Eli and Yu, Dong},
abstractNote = {Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature, and exciton condensates can be realized at much higher temperature than condensates of atoms because of strong Coulomb binding and small mass. Signatures of exciton condensation have been reported in double quantum wells, microcavities, graphene, and transition metal dichalcogenides. Nonetheless, transport of exciton condensates is not yet understood and it is unclear whether an exciton condensate is a superfluid or an insulating electronic crystal. Topological insulators (TIs) with massless particles and unique spin textures have been theoretically predicted as a promising platform for achieving exciton condensation. Here we report experimental evidence of excitonic superfluid phase on the surface of three-dimensional (3D) TIs. We unambiguously confirmed that electrons and holes are paired into charge neutral bound states by the electric field independent photocurrent distributions. And we observed a millimetre-long transport distance of these excitons up to 40 K, which strongly suggests dissipationless propagation. The robust macroscopic quantum states achieved with simple device architecture and broadband photoexcitation at relatively high temperature are expected to find novel applications in quantum computations and spintronics.},
doi = {},
journal = {arXiv.org Repository},
issn = {9999-0017},
number = ,
volume = 2018,
place = {United States},
year = {2018},
month = {10}
}