Enhancement of superconductivity upon reduction of carrier density in proximitized graphene

Gopi Nath Daptary; Udit Khanna; Eyal Walach; Arnab Roy; Efrat Shimshoni; Aviad Frydman

doi:10.1103/PhysRevB.105.L100507

Enhancement of superconductivity upon reduction of carrier density in proximitized graphene

Gopi Nath Daptary, Udit Khanna, Eyal Walach, Arnab Roy, Efrat Shimshoni, Aviad Frydman

Department of Physics

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1 Scopus citations

Abstract

The superconducting transition temperature (Tc) of single-layer graphene coupled to an indium oxide (InO) film, a low carrier-density superconductor, is found to increase with decreasing carrier density and is largest close to the average charge neutrality point in graphene. Such an effect is very surprising in conventional BCS superconductors. We study this phenomenon both experimentally and theoretically. Our analysis suggests that the InO film induces random electron and hole doped puddles in the graphene. The Josephson effect across these regions of opposite polarity enhances the Josephson coupling between the superconducting clusters in InO, along with the overall Tc of the bilayer heterostructure. This enhancement is most effective when the chemical potential of the system is tuned between the charge neutrality points of the electron and hole doped regions.

Original language	English
Article number	L100507
Journal	Physical Review B
Volume	105
Issue number	10
DOIs	https://doi.org/10.1103/PhysRevB.105.L100507
State	Published - 1 Mar 2022

Bibliographical note

Publisher Copyright:
© 2022 American Physical Society.

Funding

We are grateful for help from I. Volotsenko, and useful discussions with J. Ruhman and N. Trivedi. G.N.D., A.R., and A.F. were supported by the Israel Science fund, ISF, Grant No. 1499/21 and the U.S.-Israel Binational Science Foundation (BSF) Grant No. 2020331. U.K., E.W., and E.S. were supported by Israel Science Foundations (ISF) Grant No. 993/19, and the U.S.-Israel Binational Science Foundation (BSF) Grants No. 2016130 and No. 2018726.

Funders	Funder number
Israel Science fund, ISF	1499/21
United States-Israel Binational Science Foundation	2020331
Israel Science Foundation	2016130, 2018726, 993/19

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10.1103/PhysRevB.105.L100507

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abstract = "The superconducting transition temperature (Tc) of single-layer graphene coupled to an indium oxide (InO) film, a low carrier-density superconductor, is found to increase with decreasing carrier density and is largest close to the average charge neutrality point in graphene. Such an effect is very surprising in conventional BCS superconductors. We study this phenomenon both experimentally and theoretically. Our analysis suggests that the InO film induces random electron and hole doped puddles in the graphene. The Josephson effect across these regions of opposite polarity enhances the Josephson coupling between the superconducting clusters in InO, along with the overall Tc of the bilayer heterostructure. This enhancement is most effective when the chemical potential of the system is tuned between the charge neutrality points of the electron and hole doped regions.",

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Enhancement of superconductivity upon reduction of carrier density in proximitized graphene

Abstract

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