Epitaxial vanadium nanolayers to suppress interfacial reactions during deposition of titanium-bearing Heusler alloys on MgO(001)

Abstract Epitaxial growth of the half-Heusler alloy TiNiSn onto (100)-oriented MgO is compromised by interfacial reactions driven by the oxidising potential of titanium. Here, we demonstrate that a few epitaxial monolayers of elemental vanadium are sufficient to act as an impermeable buffer that maintains epitaxy and stoichiometric thin film growth but suppresses interfacial oxidation of the alloy. Electron diffraction and microscopy are used to characterise the thin film morphologies and thereby determine the optimum deposition conditions. Electron energy loss spectroscopy is used to demonstrate the chemical nature of the resulting thin film interfaces and confirms that TiNiSn film quality is improved.