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

Abstract

Superconductivity in the family of spinel oxides is very rare owing to their robust Mott-insulating nature. About half a century ago, LiTi${}_2$O${}_4$ became the first reported spinel compound to show superconductivity with a 12K transition temperature. Since then, several unsuccessful attempts were made to enhance the T${}_c$ of this family of materials. However, a very recent experiment [arXiv:2209.02053] has reported superconductivity at a higher temperature (below 16K), in the V-doped Mg${}_{1-\delta }$Ti${}_2$O${}_4$ thin surface layer while its bulk counterpart remains Mott insulating. The superconducting T${}_c$ of this material is significantly higher compared to other engineered MgTi${}_2$O${}_4$ thin films grown on different substrates. From our first-principles analysis, we have identified that Mg-depletion significantly reduces Jahn-Teller (JT) activity and antiferromagnetic superexchange at the surface layer of V-doped MgTi${}_2$O${}_4$ due to considerable charge transfer between various ions. The combined effect of a degraded antiferromagnetic order and reduced JT activity weakens the Mottness of the system, leading to the emergence of superconductivity at higher temperatures.

arXiv commentMaine article - 12 pages (single column), 4 figures. Supplemental attached

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Cited by in corpus (2)

• Surface-phase superconductivity in Mg-deficient V-doped MgTi${}_2$O${}_4$ spinel
• Exploring the Electronic Nature of Spinel Oxides: A Review of Their Electron Interactions and Prospects