When Superconductivity Crosses Over: From BCS to BEC

Fuente: arXiv
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Autores principales: Chen, Qijin, Wang, Zhiqiang, Boyack, Rufus, Yang, Shuolong, Levin, K.
Formato: Preprint
Publicado: 2022
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author Chen, Qijin
Wang, Zhiqiang
Boyack, Rufus
Yang, Shuolong
Levin, K.
author_facet Chen, Qijin
Wang, Zhiqiang
Boyack, Rufus
Yang, Shuolong
Levin, K.
contents New developments in superconductivity, particularly through unexpected and often astonishing forms of superconducting materials, continue to excite the community and stimulate theory. It is now becoming clear that there are two distinct platforms for superconductivity: natural and synthetic materials. The study of these artificial materials has greatly expanded in the last decade or so, with the discoveries of new forms of superfluidity in artificial heterostructures and the exploitation of proximitization. Natural superconductors continue to surprise through the Fe-based pnictides and chalcogenides, and nickelates as well as others. It is the goal of this review to present this two-pronged investigation into superconductors, with a focus on those that we have come to understand belong somewhere between the Bardeen-Cooper-Schrieffer (BCS) and Bose-Einstein condensation (BEC) regimes. We characterize in detail the nature of this "crossover" superconductivity, which is to be distinguished from crossover superfluidity in atomic Fermi gases. In the process, we address the multiple ways of promoting a system out of the BCS and into the BCS-BEC crossover regime within the context of concrete experimental realizations. These involve natural materials, such as organic conductors, as well as artificial, mostly two-dimensional materials, such as magic-angle twisted bilayer and trilayer graphene, or gate-controlled devices, as well as one-layer and interfacial superconducting films. This work should be viewed as a celebration of BCS theory by showing that even though this theory was initially implemented with the special case of weak correlations in mind, it can in a very natural way be extended to treat the case of these more exotic strongly correlated superconductors.
format Preprint
id arxiv_https___arxiv_org_abs_2208_01774
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle When Superconductivity Crosses Over: From BCS to BEC
Chen, Qijin
Wang, Zhiqiang
Boyack, Rufus
Yang, Shuolong
Levin, K.
Superconductivity
Mesoscale and Nanoscale Physics
Quantum Gases
Strongly Correlated Electrons
New developments in superconductivity, particularly through unexpected and often astonishing forms of superconducting materials, continue to excite the community and stimulate theory. It is now becoming clear that there are two distinct platforms for superconductivity: natural and synthetic materials. The study of these artificial materials has greatly expanded in the last decade or so, with the discoveries of new forms of superfluidity in artificial heterostructures and the exploitation of proximitization. Natural superconductors continue to surprise through the Fe-based pnictides and chalcogenides, and nickelates as well as others. It is the goal of this review to present this two-pronged investigation into superconductors, with a focus on those that we have come to understand belong somewhere between the Bardeen-Cooper-Schrieffer (BCS) and Bose-Einstein condensation (BEC) regimes. We characterize in detail the nature of this "crossover" superconductivity, which is to be distinguished from crossover superfluidity in atomic Fermi gases. In the process, we address the multiple ways of promoting a system out of the BCS and into the BCS-BEC crossover regime within the context of concrete experimental realizations. These involve natural materials, such as organic conductors, as well as artificial, mostly two-dimensional materials, such as magic-angle twisted bilayer and trilayer graphene, or gate-controlled devices, as well as one-layer and interfacial superconducting films. This work should be viewed as a celebration of BCS theory by showing that even though this theory was initially implemented with the special case of weak correlations in mind, it can in a very natural way be extended to treat the case of these more exotic strongly correlated superconductors.
title When Superconductivity Crosses Over: From BCS to BEC
topic Superconductivity
Mesoscale and Nanoscale Physics
Quantum Gases
Strongly Correlated Electrons
url https://arxiv.org/abs/2208.01774