• Pal, Riju
• Goswami, D. K.
• Choudhury, D.
• Bera, K.
• Pal, A. N.
• Pal, B.
• Rahaman, A.
• Mallik, S.
• Maji, P.
• Paramanik, T.

Abstract

Around fifty years ago, LiTi$_2$O$_4$ was reported to be first spinel oxide to exhibit a superconducting transition12 K. Recently, MgTi$_2$O$_4$ has been found to be the only other spinel oxide to reveal a superconducting transition with a T$_c$ around 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 is reproducibly stabilized as a thin surface layer on top of stoichiometric and insulating V-doped MgTi$_2$O$_4$ bulk sample, exhibits high-temperature superconductivity below16 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 conformed through grazing-incidence X-ray diffraction and Micro-Raman spectroscopy. A small shift of the sharp superconducting transition temperature ( 4 K) with application of a high magnetic field (upto 9 Tesla) suggests a very high critical field for the system,25 Tesla. Thus, V-doped Mg$_{1-x}$Ti$_2$O$_4$ exhibits highest T$_c$ among spinel superconductors and also possesses a very high critical field....

Topics

• impedance spectroscopy
• surface
• phase
• x-ray diffraction
• thin film
• Raman spectroscopy
• superconductivity
• superconductivity