Crossover between Strongly-coupled and Weakly-coupled Exciton Superfluids

Fuente: arXiv
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Main Authors: Liu, Xiaomeng, Li, J. I. A., Watanabe, Kenji, Taniguchi, Takashi, Hone, James, Halperin, Bertrand I., Kim, Philip, Dean, Cory R.
Format: Preprint
Published: 2020
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author Liu, Xiaomeng
Li, J. I. A.
Watanabe, Kenji
Taniguchi, Takashi
Hone, James
Halperin, Bertrand I.
Kim, Philip
Dean, Cory R.
author_facet Liu, Xiaomeng
Li, J. I. A.
Watanabe, Kenji
Taniguchi, Takashi
Hone, James
Halperin, Bertrand I.
Kim, Philip
Dean, Cory R.
contents In fermionic systems, superconductivity and superfluidity are enabled through the condensation of fermion pairs. The nature of this condensate can be tuned by varying the pairing strength, with weak coupling yielding a BCS-like condensate and strong coupling resulting in a BEC-like process. However, demonstration of this cross-over has remained elusive in electronic systems. Here we study graphene double-layers separated by an atomically thin insulator. Under applied magnetic field, electrons and holes couple across the barrier to form bound magneto-excitons whose pairing strength can be continuously tuned by varying the effective layer separation. Using temperature-dependent Coulomb drag and counter-flow current measurements, we demonstrate the capability to tune the magneto-exciton condensate through the entire weak-coupling to strong-coupling phase diagram. Our results establish magneto-exciton condensates in graphene as a model platform to study the crossover between two Bosonic quantum condensate phases in a solid state system.
format Preprint
id arxiv_https___arxiv_org_abs_2012_05916
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Crossover between Strongly-coupled and Weakly-coupled Exciton Superfluids
Liu, Xiaomeng
Li, J. I. A.
Watanabe, Kenji
Taniguchi, Takashi
Hone, James
Halperin, Bertrand I.
Kim, Philip
Dean, Cory R.
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Superconductivity
In fermionic systems, superconductivity and superfluidity are enabled through the condensation of fermion pairs. The nature of this condensate can be tuned by varying the pairing strength, with weak coupling yielding a BCS-like condensate and strong coupling resulting in a BEC-like process. However, demonstration of this cross-over has remained elusive in electronic systems. Here we study graphene double-layers separated by an atomically thin insulator. Under applied magnetic field, electrons and holes couple across the barrier to form bound magneto-excitons whose pairing strength can be continuously tuned by varying the effective layer separation. Using temperature-dependent Coulomb drag and counter-flow current measurements, we demonstrate the capability to tune the magneto-exciton condensate through the entire weak-coupling to strong-coupling phase diagram. Our results establish magneto-exciton condensates in graphene as a model platform to study the crossover between two Bosonic quantum condensate phases in a solid state system.
title Crossover between Strongly-coupled and Weakly-coupled Exciton Superfluids
topic Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Superconductivity
url https://arxiv.org/abs/2012.05916