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

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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 · Physical Review B

T1

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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.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
InO Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.5	Pressure not reported	unknown
La2-xSrxCuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown