Superconducting Phase of $\mathrm{T}{\mathrm{i}}_{\mathrm{x}}{\mathrm{O}}_{\mathrm{y}}$ Thin Films Grown by Molecular Beam Epitaxy

Abstract

We investigate the complex relationship between the growth conditions and the structural and transport properties of $\mathrm{T}{\mathrm{i}}_{\mathrm{x}}{\mathrm{O}}_{\mathrm{y}}$ thin films grown by molecular beam epitaxy. Transport properties ranging from metallicity to superconductivity and insulating states are stabilized by effectively tuning the O/Ti ratio via the Ti flux rate and the O partial pressure, $P_{Ox}$, for films grown on (0001)-$\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$ substrates at 850${}^{\circ }$ C. A cubic $c-\mathrm{Ti}{\mathrm{O}}_{1\pm \delta }$ buffer layer is formed for low O/Ti ratios while a corundum cr-$\mathrm{T}{\mathrm{i}}_2{\mathrm{O}}_3$ layer is formed under higher oxidizing conditions. Metallicity is observed for c-$\mathrm{Ti}{\mathrm{O}}_{1-\delta }$ buffer layers. The superconducting $\gamma -\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$ Magnéli phase is found to nucleate on a c-$\mathrm{Ti}{\mathrm{O}}_{1-\delta }$ buffer for intermediate $P_{Ox}$ conditions and an insulator-superconducting transition is observed at 4.5 K (T${}_C^{onset}=6K$) for 85 nm thick films. Strain relaxation of the $\gamma -\mathrm{T}{\mathrm{i}}_3{\mathrm{O}}_5$ occurs with increasing film thickness and correlates with a thickness-dependent increase in T${}_C$ observed for $\mathrm{T}{\mathrm{i}}_{\mathrm{x}}{\mathrm{O}}_{\mathrm{y}}$ thin films.

References in corpus (1)

• Enhanced Superconductivity in TiO Epitaxial Thin Films

Cited by in corpus (1)

• In-situ scattering studies of superconducting vacancy-ordered monoclinic TiO thin films