The absence of superfluid response in ac and bc-plane optical conductivities of optimally-doped Bi2212 single crylstals in the surface region

TL;DR

This study measures optical conductivities in different planes of Bi2212 crystals and finds no superfluid response in ac and bc planes, suggesting unusual surface properties and supporting d-wave symmetry of the superconducting order parameter.

Contribution

It provides the first detailed optical conductivity measurements in multiple edge planes of Bi2212, revealing anisotropic superfluid responses and implications for surface superconductivity.

Findings

Superfluid response observed in (1ar{1}0)-plane

No superfluid response in ac and bc planes

Supports d-wave symmetry of the order parameter

Abstract

The optical properties of optimally-doped Bi_2Sr_2CaCu_2O_{8+\delta} (Bi2212) have been measured normal to the edge planes [ac plane, bc plane, and (1\bar{1}0) plane], for light polarized parallel to nodal and anti-nodal (gap) directions, respectively. While the superfluid contribution can be obtained from the optical conductivities in the (1\bar{1}0)-plane, it is unobservable in the ac and bc-planes. This apparent asymmetry implies that the edge region of high-T_c cuprates is unusual and further supports a d-wave symmetry of the superconducting order parameter.