Crossover between strongly coupled and weakly coupled exciton superfluids
Crossover between strongly coupled and weakly coupled exciton superfluids
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DOI：
10.1126/science.abg1110
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发表时间：
2022-01-14
期刊：
影响因子：
56.9
通讯作者：
Dean, Cory R.
中科院分区：
文献类型：
--
作者：
Liu, Xiaomeng;Li, J. I. A.;Dean, Cory R.
在费米子系统中，超导性和超流性通过费米子对的凝聚而发生。这种凝聚物的性质可以通过改变配对强度来调整，这在电子系统中是具有挑战性的。我们研究了由原子级薄绝缘体隔开的石墨烯双层。在外加磁场下，电子和空穴耦合穿过势垒以形成束缚磁激子，其配对强度可以通过改变有效层间距来连续调节。使用随温度变化的库仑阻力和逆流电流测量，我们能够通过整个相图从弱到强耦合调整磁激子凝聚体。我们的研究结果建立了石墨烯中的磁激子凝聚体作为模型平台来研究固态系统中两个玻色子量子凝聚相之间的交叉。
In fermionic systems, superconductivity and superfluidity occur through the condensation of fermion pairs. The nature of this condensate can be tuned by varying the pairing strength, which is challenging in electronic systems. We studied 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 counterflow current measurements, we were able to tune the magneto-exciton condensate through the entire phase diagram from weak to strong coupling. 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.