Fermi-surface induced modulation in an optimally doped YBCO superconductor

TL;DR

This study reveals a Fermi-surface induced lattice modulation in an optimally doped YBCO superconductor, linked to charge-density wave phenomena, with specific wavevector characteristics and occurrence within oxygen-vacancy-ordered regions.

Contribution

The paper reports the discovery of a Fermi-surface induced lattice modulation in YBCO, demonstrating a connection to charge-density waves and detailing its dependence on oxygen-vacancy ordering.

Findings

Fermi-surface induced lattice modulation with wavevector q1=(0, δ, 0)

Modulation exists only within oxygen-vacancy-ordered islands

Modulation persists above and below the superconducting transition temperature

Abstract

We have observed a Fermi-surface (FS) induced lattice modulation in a YBCO superconductor with a wavevector along CuO chains, {\it i.e.} ${\bf q}_1$=(0,$\delta$,0). The value of $\delta\sim0.21$ is twice the Fermi wavevector ($2{\bf k}_F$) along {\bf b*} connecting nearly nested FS `ridges'. The ${\bf q}_1$ modulation exists only within O-vacancy-ordered islands (characterized by ${\bf q}_0$=$(\frac14,0,0))$ and persists well above and below $T_c$. Our results are consistent with the presence of a FS-induced charge-density wave.