High-T_c superconductivity in ultrathin Bi_2Sr_2CaCu_2O_8+x down to halfunit-cell thickness by protection with graphene

Abstract

High-T_c superconductors confined to two dimension exhibit novel physical phenomena, such as superconductor-insulator transition. In the Bi_2Sr_2CaCu_2O_8+x (Bi2212) model system, despite extensive studies, the intrinsic superconducting properties at the thinness limit have been difficult to determine. Here we report a method to fabricate high quality single-crystal Bi2212 films down to half-unit-cell thickness in the form of graphene/Bi2212 van der Waals heterostructure, in which sharp superconducting transitions are observed. The heterostructure also exhibits a nonlinear current-voltage characteristic due to the Dirac nature of the graphene band structure. More interestingly, although the critical temperature remains essentially the same with reduced thickness of Bi2212, the slope of the normal state T-linear resistivity varies by a factor of 4-5, and the sheet resistance increases by three orders of magnitude, indicating a surprising decoupling of the normal state resistance and superconductivity. The developed technique is versatile, applicable to investigate other two-dimensional (2D) superconducting materials.

23 pages, 4 figures

References in corpus (6)

• Electric Field Effect in Atomically Thin Carbon Films
• Two Dimensional Atomic Crystals
• Vertical Field Effect Transistor based on Graphene-WS2 Heterostructures for flexible and transparent electronics
• Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices
• High-temperature interface superconductivity between metallic and insulating cuprates
• Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin cuprate films

Cited by in corpus (8)

• Highly crystalline 2D superconductors
• Two-dimensional Superconductors with Atomic-scale Thicknesses
• Two-dimensional topological superconductivity candidate in van der Waals layered material
• Prominent Josephson tunneling between twisted single copper oxide planes of Bi${}_2$Sr${}_{2-x}$LaxCuO${}_{6+y}$
• Superconducting FeSe monolayer with milli-electron volt Fermi energy
• On-demand local modification of high-$T_{\text{c}}$ superconductivity in few unit-cell thick Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$
• Quasi two-dimensional nature of high-Tc superconductivity in iron-based (Li,Fe)OHFeSe
• Little-Parks like oscillations in lightly doped cuprate superconductors