Photoemission Evidence for a Remnant Fermi Surface and d-Wave-Like Dispersion in Insulating Ca2CuO2Cl2

TL;DR

This study uses photoemission to reveal a remnant Fermi surface and d-wave-like dispersion in the insulating Ca2CuO2Cl2, providing insights into the pseudogap phenomenon in high-temperature superconductors.

Contribution

It provides the first evidence of a remnant Fermi surface and d-wave-like dispersion in an insulating parent compound of high-Tc superconductors.

Findings

Remnant Fermi surface observed in Ca2CuO2Cl2

Dispersion follows |cos(kxa)-cos(kya)| form

Suggests d-wave-like dispersion underlies the pseudogap

Abstract

An angle resolved photoemission study on Ca2CuO2Cl2, a parent compound of high Tc superconductors is reported. Analysis of the electron occupation probability, n(k) from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the |cos(kxa)-cos(kya)| form along this remnant Fermi surface. Together with the data from Dy doped Bi2Sr2CaCu2O(8 + delta) these results suggest that this d-wave like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime.