Imprint of charge and oxygen orders on Dy ions in DyBa$_2$Cu$_3$O$_{6+x}$ thin films probed by resonant x-ray scattering

TL;DR

This study uses resonant x-ray scattering to reveal how charge and oxygen orders influence Dy ions in DyBa$_2$Cu$_3$O$_{6+x}$ thin films, showing induced order on the rare-earth sublattice and magnetic field effects.

Contribution

It demonstrates the presence of charge and oxygen order effects on Dy ions in DyBCO thin films using resonant x-ray scattering, revealing induced ordered states on the rare-earth sublattice.

Findings

Diffraction peaks at Dy M5 edge match charge density wave wavevectors.

Resonant diffraction intensity varies non-monotonically with magnetic field.

Model calculations explain the modulation of Dy electric field by charge and oxygen order.

Abstract

We used resonant elastic x-ray scattering at the Cu $L_3$ and Dy $M_5$ edges to investigate charge order in thin films of underdoped DyBa$_2$Cu$_3$O$_{6+x}$ (DyBCO) epitaxially grown on NdGaO$_3$ (110) substrates. The films show an orthorhombic crystal structure with short-range ortho-II oxygen order in the charge-reservoir layers. At the Dy $M_5$ edge we observe diffraction peaks with the same planar wavevectors as those of the two-dimensional charge density wave in the CuO$_2$ planes and of the ortho-II oxygen order, indicating the formation of induced ordered states on the rare-earth sublattice. The intensity of the resonant diffraction peaks exhibits a non-monotonic dependence on an external magnetic field. Model calculations on the modulation of the crystalline electric field at the Dy sites by charge and oxygen order capture the salient features of the magnetic field, temperature, and photon energy dependence of the scattering intensity.