Structural effect on the static spin and charge correlations in La$_{1.875}$Ba$_{0.125-x}$Sr$_{x}$CuO$_{4}$

TL;DR

This study investigates how structural phase transitions in La-based cuprates influence static spin and charge correlations, revealing that symmetry changes affect the orientation and relation of CDW and SDW wavevectors.

Contribution

It provides new insights into the relationship between crystal symmetry and electronic orderings in La$_{1.875}$Ba$_{0.125-x}$Sr$_{x}$CuO$_{4}$, highlighting the impact of structural phases on wavevector orientations.

Findings

Charge and spin wavevectors tilt in low-symmetry phases.

Wavevectors align along high-symmetry axes in tetragonal phase.

Correlation between CuO$_{2}$ plane corrugation and wavevector deviations.

Abstract

We report the results of elastic neutron scattering measurements performed on 1/8-hole doped La$_{1.875}$Ba$_{0.125-x}$Sr$_{x}$CuO$_{4}$ single crystals with {\it x}=0.05, 0.06, 0.075 and 0.085. In the low-temperature less-orthorhombic (LTLO, {\it Pccn} symmetry) phase, the charge-density-wave (CDW) and spin-density-wave (SDW) wavevectors were found to tilt in a low-symmetric direction with one-dimensional anisotropy in the CuO$_{2}$ plane, while they were aligned along the high-symmetry axis in the low-temperature tetragonal (LTT, {\it P}4$_2$/{\it ncm} symmetry) phase. The coincident direction of two wavevectors suggests a close relation between CDW and SDW orders. The SDW wavevector systematically deviates from the Cu-O bond direction in the LTLO phase upon Sr substitution and the tilt angle in the LTLO phase is smaller than that in the low-temperature orthorhombic phase (LTO, {\it B}{\it mab} symmetry) with comparable in-plane orthorhombic distortion. These results demonstrate a correlation between the corrugated pattern of CuO$_{2}$ plane and the deviations.