Surface-phase superconductivity in Mg-deficient V-doped MgTi${}_2$O${}_4$ spinel

Abstract

Around fifty years ago, LiTi${}_2$O${}_4$ was reported to be first spinel oxide to exhibit a superconducting transition with highest T${}_c$ $\approx$ 13.7 K. Recently, MgTi${}_2$O${}_4$ has been found to be the only other spinel oxide to reveal a superconducting transition with a T${}_c$ $\approx$ 3 K, however, its superconducting state is realized only in thin film superlattices involving SrTiO${}_3$. We find that a V-doped Mg${}_{1-x}$Ti${}_2$O${}_4$ phase, which gets stabilized as a thin surface layer on top of stoichiometric and insulating V-doped MgTi${}_2$O${}_4$ bulk sample, exhibits high-temperature superconductivity with T${}_c$ $\approx$ 16 K. The superconducting transition is also confirmed through a concomitant sharp diamagnetic transition immediately below T${}_c$. The spinel phase of the superconducting surface layer is elucidated through grazing-incidence X-ray diffraction and Micro-Raman spectroscopy. A small shift of the sharp superconducting transition temperature ($\sim$ 4 K) with application of a high magnetic field (upto 9 Tesla) suggests a very high critical field for the system, $\sim$ 25 Tesla. Thus, V-doped Mg${}_{1-x}$Ti${}_2$O${}_4$ exhibits the highest T${}_c$ among spinel superconductors and also possesses a very high critical field.

5 pages, 4 figures

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• Upper critical fields and thermally-activated transport of Nd(O_0.7F_0.3)FeAs single crystal
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• Superconductivity with the enhanced upper critical field in the Pt-Doping CuRh2Se4 spinel
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• Epitaxial stabilization of an orthorhombic Mg-Ti-O superconductor

Cited by in corpus (1)

• Exploring the Electronic Nature of Spinel Oxides: A Review of Their Electron Interactions and Prospects