Direct observation of particle-hole mixing in the superconducting state by angle-resolved photoemission

TL;DR

This paper provides direct experimental evidence of particle-hole mixing in the superconducting state of Bi_2Sr_2CaCu_2O_{8+\delta} using ARPES, confirming the superconducting origin of the observed energy gap.

Contribution

It presents the first direct ARPES observation of particle-hole mixing in a superconductor, confirming the gap's link to superconductivity.

Findings

Evidence of particle-hole mixing in ARPES spectra

Confirmation that the energy gap is associated with superconductivity

Establishment of the fundamental role of particle-hole mixing in superconductors

Abstract

Particle-hole (p-h) mixing is a fundamental consequence of the existence of a pair condensate. We present direct experimental evidence for p-h mixing in the angle-resolved photoemission (ARPES) spectra in the superconducting state of Bi_2Sr_2CaCu_2O_{8+\delta}. In addition to its pedagogical importance, this establishes unambiguously that the gap observed in ARPES is associated with superconductivity.