Flexible Epsilon Iron Oxide Thin Films

Metastable ε-Fe₂O₃ is a unique phase of iron oxide, which exhibits a giant coercivity field. In this work, we grew epitaxial ε-Fe₂O₃ films on flexible two-dimensional muscovite substrates via quasi van der Waals epitaxy. It turns out that twinning and interface energies have been playing essential roles in stabilizing metastable ε-Fe₂O₃ on mica substrates. Moreover, the weak interfacial bonding between ε-Fe₂O₃ and mica is expected to relieve the substrate clamping effect ubiquitously encountered in films epitaxially grown on rigid substrates, such as SrTiO₃. It is anticipated that these flexible ε-Fe₂O₃ thin films can serve as a platform for exploring possible interesting emergent physical properties and eventually be integrated as flexible functional devices.