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

TL;DR

This study investigates V$_2$Ga$_5$, a superconductor with a quasi-one-dimensional structure, revealing potential proximity to ferromagnetic order that coexists with superconductivity and is supported by experimental and theoretical evidence.

Contribution

It provides the first comprehensive experimental and DFT analysis suggesting V$_2$Ga$_5$ is near ferromagnetic instability, highlighting the interplay between superconductivity and magnetism.

Findings

Magnetic susceptibility shows ZFC/FC splitting below 10 K.

Resistivity upturn depends on magnetic field.

DFT indicates Fermi level at a density of states peak.

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 ($T_c = 3.54 \ K$) with a quasi-one-dimensional crystal structure, supplemented with density functional theory (DFT) calculations, suggesting possible proximity to ferromagnetic order. Below $T \approx 10 \ K$, 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 $T \approx 10 \ K$, well above $T_c$, with long-range ferromagnetic order suppressed by the superconducting transition.