Stabilization of high-pressure GeCu$_{2}$O$_{4}$ spinel cuprate with quasi-1D $S=1/2$ chains in the epitaxial thin-film form

TL;DR

This study reports the first successful growth of epitaxial thin films of GeCu₂O₄, a high-pressure cuprate with a unique magnetic chain structure, enabling future exploration of its magnetic and multiferroic properties.

Contribution

The paper demonstrates the first stabilization of high-quality epitaxial thin films of GeCu₂O₄, facilitating detailed physical property investigations.

Findings

Successful growth of GeCu₂O₄ thin films on MgAl₂O₄ substrate.

Comprehensive characterization of film structure and composition.

Potential for studying magnetism and multiferroicity in GeCu₂O₄.

Abstract

GeCu$_2$O$_4$ is a high-pressure recoverable cuprate with a strongly tetragonally elongated spinel structure and magnetic lattice formed by $S=1/2$ CuO$_2$ linear chains with frustrated exchange interactions and exotic magnetic behavior. Here we report on the first stabilization of epitaxial thin films of GeCu$_2$O$_4$ on (001)-oriented MgAl$_2$O$_4$ substrate. Developed growth mode, surface morphology, crystal structure and copper valence state were characterized by \emph{in-situ} reflection high-energy electron diffraction, atomic force microscopy, X-ray reflectivity, X-ray diffraction and X-ray photoelectron spectroscopy. The availability of large single-crystalline GeCu$_2$O$_4$ thin films paves road to comprehensive investigation of physical properties including the puzzle of magnetism and multiferroicity in this peculiar compound.