Crystal Symmetry of Stripe Ordered La1.88Sr0.12CuO4

TL;DR

This study combines x-ray and neutron diffraction to analyze the crystal symmetry of stripe-ordered La1.88Sr0.12CuO4, revealing monoclinic distortions consistent with charge stripe order, challenging the previously assumed orthorhombic symmetry.

Contribution

It demonstrates that the average orthorhombic structure is incompatible with stripe order, uncovering monoclinic distortions through forbidden Bragg peaks analysis.

Findings

Detection of forbidden Bragg peaks indicating symmetry breaking.

Identification of monoclinic lattice distortions.

Correlation of distortions with charge stripe order.

Abstract

We present a combined x-ray and neutron diffraction study of the stripe ordered superconductor \lscox{0.12}. The average crystal structure is consistent with the orthorhombic $Bmab$ space group as commonly reported in the literature. This structure however is not symmetry compatible with a second order phase transition into the stripe order phase, and, as we report here numerous Bragg peaks forbidden in the $Bmab$ space group are observed. We have studied and analysed these $Bmab$-forbidden Bragg reflections. Fitting of the diffraction intensities yields monoclinic lattice distortions that are symmetry consistent with charge stripe order.