Possible Proximity to Ferromagnetism in the V${}_2$Ga${}_5$ Superconductor

Abstract

Superconductivity and ferromagnetism are generally competing ground states in $d$-electron systems, making their interplay of fundamental interest. We report a comprehensive study of high-quality single- and polycrystalline V${}_2$Ga${}_5$, a bulk type-II superconductor ($T_c=3.54K$) with a quasi-one-dimensional crystal structure, supplemented with density functional theory (DFT) calculations, suggesting possible proximity to ferromagnetic order. Below $T\approx 10K$, magnetic susceptibility shows ZFC/FC splitting, along with saturation and hysteresis in $M(H)$. Moreover, electrical transport measurements reveal a magnetic-field-dependent resistivity upturn, while specific heat is enhanced in magnetic fields. DFT calculations show that the Fermi level in V${}_2$Ga${}_5$ is located at a peak in the density of states, with a small magnetic moment per unit cell comparable to the experimental value. Together, these results indicate the possibility that ferromagnetic correlations develop below $T\approx 10K$, well above $T_c$, with long-range ferromagnetic order suppressed by the superconducting transition.

13 pages, 8 figures