Lower Bound on the Energy Gap at Precise Locations on the Bi_2Sr_2CaCu_2O_8 Fermi Surface

TL;DR

This paper establishes a lower bound on the energy gap at specific points on the Fermi surface of Bi_2Sr_2CaCu_2O_8 using neutron scattering data, aiding in understanding its superconducting gap symmetry.

Contribution

It introduces a method to determine the lower bound of the energy gap at precise Fermi surface locations using inelastic neutron scattering measurements.

Findings

Lower bound on the energy gap at specific Fermi surface points.

Potential to identify d_{x^2-y^2} gap symmetry.

Framework for angle-resolved gap mapping.

Abstract

Recent inelastic-neutron-scattering measurements of a low-energy phonon in Bi_2Sr_2CaCu_2O_8 provide enough information to place a lower bound on the energy gap magnitude at precise locations on the Fermi surface. Measurements of a few low-energy phonons should indicate whether the gap symmetry is d_{x^2-y^2}. Further measurements could map out the angle-resolved gap magnitude on the entire Fermi surface.