# Epitaxial stabilization of thin films of the frustrated Ge-based spinels

## TL;DR

This paper reports the successful epitaxial growth of thin films of GeNi2O4 and GeCu2O4, enabling new experimental access to their exotic magnetic properties and strain-induced phenomena in frustrated spinel materials.

## Contribution

First demonstration of epitaxial stabilization of GeNi2O4 and GeCu2O4 thin films, facilitating advanced studies of their magnetic behaviors and strain effects.

## Key findings

- Achieved high-quality epitaxial thin films of the compounds.
- Characterized surface morphology and crystal structure.
- Established a new route for magnetic property investigation.

## Abstract

Frustrated magnets can host numerous exotic many-body quantum and topological phenomena. GeNi$_2$O$_4$ is a three dimensional $S=1$ frustrated magnet with an unusual two-stage transition to the two-dimensional antiferromagnetic ground state, while GeCu$_2$O$_4$ is a high-pressure phase 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 thin-film epitaxial stabilization of these two compounds. Developed growth mode, surface morphology, crystal structure and copper valence state were characterized by in-situ reflection high-energy electron diffraction, atomic force microscopy, X-ray reflectivity, X-ray diffraction, X-ray photoelectron spectroscopy and resonant X-ray absorption spectroscopy. Our results pave an alternative route to the comprehensive investigation of the puzzling magnetic properties of these compounds and exploration of novel emergent features driven by strain.