Preparation of hexagonal iron flakes with a hexagonal structure on the sublayer of copper oxides

The stabilization of hexagonal close-packed (hcp) iron at ambient conditions remains a significant challenge due to its metastable nature. Here, we report a novel and facile strategy for templating the epitaxial growth of hcp-Fe flakes using tailored copper oxide sublayers. By simply varying the sublayer annealing temperature, we achieved precise control over the iron morphology, obtaining uniform hexagonal hcp-Fe flakes on optimally prepared surfaces. Structural analysis confirms the successful stabilization of hcp-Fe, revealing a coherent epitaxial relationship between hcp-Fe(002) and CuO(- 112). Crucially, the stabilized hcp-Fe exhibits antiferromagnetic ordering, as demonstrated by vibrating sample magnetometry (VSM) and density functional theory (DFT) calculations, contrasting the ferromagnetism of bulk bcc-Fe. This work provides a facile and scalable pathway to synthesize and study hcp-Fe without extreme pressures, offering substantial potential for fundamental geophysical research and applications in antiferromagnetic spintronics and catalysis.