Emergent superconductivity in single crystalline ${\mathrm{MgTi}}_2{\mathrm{O}}_4$ films via structural engineering

Abstract

Spinel compounds have demonstrated rich functionalities but rarely shown superconductivity. Here, we report the emergence of superconductivity in the spinel ${\mathrm{MgTi}}_2{\mathrm{O}}_4$, known to be an insulator with a complicated order. The superconducting transition is achieved by engineering a superlattice of ${\mathrm{MgTi}}_2{\mathrm{O}}_4$ and ${\mathrm{SrTiO}}_3$. The onset transition temperature in the ${\mathrm{MgTi}}_2{\mathrm{O}}_4$ layer can be tuned from 0 to 5 K in such geometry, concurrently with a stretched $c$-axis (from 8.51 to 8.53 Å) compared to the bulk material. Such a positive correlation without saturation suggests ample room for the further enhancement. Intriguingly, the superlattice exhibits isotropic upper critical field $H_{\mathrm{c}2}$ that breaks the Pauli limit, distinct from the highly anisotropic feature of interface superconductivity. The origin of superconductivity in the ${\mathrm{MgTi}}_2{\mathrm{O}}_4$ layer is understood in combination with the electron energy loss spectra and the first-principles electronic structure calculations, which point to the birth of superconductivity in the ${\mathrm{MgTi}}_2{\mathrm{O}}_4$ layer by preventing the Ti-Ti dimerization. Our discovery not only provides a platform to explore the interplay between the superconductivity and other exotic states, but also opens a new window to realize superconductivity in the spinel compounds as well as other titanium oxides.

arXiv comment5 pages, 4 figures

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Cited by in corpus (8)

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• Superconductivity with the enhanced upper critical field in the Pt-Doping CuRh2Se4 spinel
• Ionic liquid gating induced two superconductor-insulator phase transitions in spinel oxide Li${}_{1\pm x}$Ti${}_2$O${}_{4-\delta }$
• Possible routes to superconductivity in the surface layers of V-doped Mg${}_{1-\delta }$Ti${}_2$O${}_4$ through multiple charge transfers and suppression of Jahn-Teller activity
• Epitaxial stabilization of an orthorhombic Mg-Ti-O superconductor
• Quantum Griffiths singularity in a three-dimensional superconductor to Anderson critical insulator transition
• Surface-phase superconductivity in Mg-deficient V-doped MgTi${}_2$O${}_4$ spinel
• Evolution of orbital excitations from insulating to superconducting MgTi${}_2$O${}_4$ films