Screening of pair fluctuations in superconductors with coupled shallow and deep bands: A route to higher-temperature superconductivity

Year: 2019

Authors: Salasnich L., Shanenko AA., Vagov A., Aguiar JA., Perali A.

Autors Affiliation: Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; CNR, INO, Sez Sesto Fiorentino, Via Nello Carrara 2, I-50019 Sesto Fiorentino, Italy; Univ Fed Pernambuco, Dept Fis, Av Jorn Anibal Fernandes S-N,Cidade Univ, BR-50740560 Recife, PE, Brazil; Bayreuth Univ, Inst Theoret Phys 3, D-95440 Bayreuth, Germany; ITMO Univ, 49 Kronverksky Pr, St Petersburg 197101, Russia; Univ Camerino, Phys Unit, Sch Pharm, I-62032 Camerino, Italy.

Abstract: A combination of strong Cooper pairing and weak superconducting fluctuations is crucial to achieve and stabilize high-T-c, superconductivity. We demonstrate that a coexistence of a shallow carrier band with strong pairing and a deep band with weak pairing, together with the Josephson-like pair transfer between the bands to couple the two condensates, realizes an optimal multicomponent superconductivity regime: it preserves strong pairing to generate large gaps and a very high critical temperature but screens the detrimental superconducting fluctuations, thereby suppressing the pseudogap state. Surprisingly, we find that the screening is very efficient even when the interband coupling is very small. Thus, a multiband superconductor with a coherent mixture of condensates in the BCS regime (deep band) and in the BCS-BEC crossover regime (shallow band) offers a promising route to higher critical temperatures.

Journal/Review: PHYSICAL REVIEW B

Volume: 100 (6)      Pages from: 064510-1  to: 064510-9

More Information: The authors acknowledge support from the Brazilian agencies Conselho Nacional de Ciencia e Tecnologia, CNPq (Grants No. 307552/2012-8, No. 309374/2016-2, and No. 484504/2013-4) and Funadacao de Amparo a Ciencia e Tecnologiado Estado de Pernambuco, FACEPE (APQ-0936-1.05/15). A.P. acknowledges the financial support from Universidade Federal de Pernambuco (Grant No. 23076.006072/2015-77) during his visit in 2015, and also the financial support from the ItalianMIUR through the PRIN 2015 program, Contract No. 2015C5SEJJ001. A.S. and A.V. acknowledge the hospitality of the Departamento de Fisica da Universidade Federal de Pernambuco during their temporary stays in the years 2013-2017, and the financial support from CNPq (Grants No. 452740/2013-4 and No. 400510/2014-6) and FACEPE (Grant No. ARC 0249-1/13). L.S. acknowledges partial support from FFABR grant of Italian MIUR. A.V. acknowledges support from the Russian Science Foundation, Project 18-12-00429. The authors thank A. Bianconi, P. Pieri, and A. A. Varlamov for useful discussions and acknowledge the collaboration within the MultiSuper International Network [55].
KeyWords: PHASE; BCS; CROSSOVER
DOI: 10.1103/PhysRevB.100.064510

Citations: 39
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