Hyperbolic Cooper-pair polaritons (HCP) in cuprate superconductors are of fundamental interest due to their potential for providing insights into the nature of unconventional superconductivity. Here, we critically assess an experimental approach using near-field imaging to probe HCP in Bi2Sr2CaCu2O8+x (Bi-2212) in the presence of graphene surface plasmon polaritons (SPP). Our simulations show that inherently weak HCP features in the near-field can be strongly enhanced when coupled to graphene SPP in layered graphene/hexagonal boron nitride (hBN)/Bi-2212 heterostructures. This enhancement arises from our multilayered structures effectively acting as plasmonic cavities capable of altering collective modes of a layered superconductor by modifying its electromagnetic environment. The degree of enhancement can be selectively controlled by tuning the insulating spacer thickness with atomic precision. Finally, we verify the expected renormalization of room-temperature graphene SPP using near-field infrared imaging. Our modeling, augmented with data, attests to the validity of our approach for probing HCP modes in cuprate superconductors.
Bibliographical noteFunding Information:
Research on hybrid heterostructures was supported by the Center on Precision-Assembled Quantum Materials, funded through the U.S. National Science Foundation (NSF) Materials Research Science and Engineering Centers (award no. DMR-2011738). D.N.B. is Moore Investigator in Quantum Materials EPIQS #9455 and the Vannevar Bush Faculty Fellow ONR-VB: N00014-19-1-2630. M.M.F. acknowledges support from ONR-N000141812722. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, Grant JPMXP0112101001, JSPS KAKENHI Grant JP20H00354, and the CREST(JPMJCR15F3), JST. The work at BNL was supported by the US Department of Energy, office of Basic Energy Sciences, contract no. DOE-sc0012704. R.D.A. acknowledges support from ARO Award No. W911NF-16-1-0361.
- Cuprate superconductors
- hyperbolic Cooper-pair polaritons
- plasmonic cavities
- scattering-type scanning near-field microscopy
- van der Waals heterostructures