# Growth of layered Lu$_2$Fe$_3$O$_7$ and Lu$_3$Fe$_4$O$_{10} $ single crystals exhibiting long-range charge order via the optical floating-zone method

## TL;DR

This study successfully grew high-quality layered Lu$_2$Fe$_3$O$_7$ and Lu$_3$Fe$_4$O$_{10}$ crystals exhibiting charge order, revealing different superstructures and magnetic properties, advancing understanding of charge ordering in intercalated iron oxides.

## Contribution

First synthesis of stoichiometric intercalated Lu-iron oxides with observable charge order superstructures using the optical floating-zone method.

## Key findings

- Observation of superstructure reflections indicating charge order.
- Identification of two distinct superstructures in Lu$_2$Fe$_3$O$_7$.
- Reduced magnetic correlations and no antiferromagnetic phase.

## Abstract

We report the controlled growth of single crystals of intercalated layered Lu$ _{1+n} $Fe$ _{2+n} $O$ _{4+3n-\delta} $ ($ n $=1,2) with different oxygen stoichiometries ${\delta}$. For the first time crystals sufficiently stoichiometric to exhibit superstructure reflections in X-ray diffraction attributable to charge ordering were obtained. The estimated correlation lengths tend to be smaller than for not intercalated LuFe$ _2 $O$ _4$. For Lu$ _2 $Fe$ _3 $O$ _7 $, two different superstructures were observed, one an incommensurate zigzag pattern similar to previous observations by electron diffraction, the other an apparently commensurate pattern with ($\frac{1}{3}\frac{1}{3}0$) propagation. Implications for the possible charge order in the bilayers are discussed. Magnetization measurements suggest reduced magnetic correlations and the absence of an antiferromagnetic phase.