Zn-impurity effects on quasi-particle scattering in La2-xSrxCuO4 studied by angle-resolved photoemission spectroscopy

TL;DR

This study uses angle-resolved photoemission spectroscopy to examine how Zn impurities affect the electronic structure and scattering processes in La2-xSrxCuO4, revealing isotropic quasi-particle broadening and gap reduction.

Contribution

It provides detailed insights into the effects of Zn impurities on quasi-particle scattering and the superconducting gap in LSCO, highlighting potential scattering near the unitarity limit.

Findings

Zn impurities cause isotropic increase in quasi-particle width

Residual resistivity increase aligns with MDC width for x=0.17

Superconducting gap is reduced near (pi,0) with Zn doping

Abstract

Angle-resolved photoemission measurements were performed on Zn-doped La2-xSrxCuO4 (LSCO) to investigate the effects of Zn impurities on the low energy electronic structure. The Zn-impurity-induced increase in the quasi-particle (QP) width in momentum distribution curves (MDC) is approximately isotropic on the entire Fermi surface and energy-independent near the Fermi level (EF). The increase in the MDC width is consistent with the increase in the residual resistivity due to the Zn impurities if we assume the carrier number to be 1-x for x=0.17 and the Zn impurity to be a potential scatterer close to the unitarity limit. For x=0.03, the residual resistivity is found to be higher than that expected from the MDC width, and the effects of antifferomagnetic fluctuations induced around the Zn impurities are discussed. The leading edges of the spectra near (pi,0) for x=0.17 are shifted toward higher energies relative to EF with Zn substitution, indicating a reduction of the superconducting gap.