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

Autor: Dey, Dibyendu, Maitra, T., Taraphder, A.
Rok vydání: 2022
Předmět:
Zdroj: Phys. Rev. B 107, 174515 (2023)
Druh dokumentu: Working Paper
DOI: 10.1103/PhysRevB.107.174515
Popis: 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.
Comment: Maine article - 12 pages (single column), 4 figures. Supplemental attached
Databáze: arXiv