Comments on gap anisotropy and nodal constant Fermi velocity in a superconductor, BSCCO

TL;DR

This paper challenges previous interpretations of gap anisotropy and Fermi velocity in BSCCO superconductors, attributing observed phenomena to measurement effects and phase transitions rather than intrinsic properties.

Contribution

It provides a reinterpretation of experimental data, suggesting that the large gap anisotropy and constant Fermi velocity are not intrinsic but due to inhomogeneity and phase transition effects.

Findings

Large gap anisotropy is not intrinsic, but due to measurement effects.

Constant Fermi velocity at the node results from insulator-metal transition.

Reinterpretation of previous experimental evidence.

Abstract

On the basis of both the inhomogeneity of a superconductor, BSCCO-2212, and the effect of measurement, we reveal that an anomalously large gap anisotropy known as evidence of dx2-y2-wave symmetry [Phys. Rev. Lett. 70 (1993) 1553] is not intrinsic, and that the constant Fermi velocity at node as an unsolved problem [Nature 423 (2003) 398] is due to the dx2-y2-wave insulator-metal transition.