Physical properties and electronic structure of the two-gap superconductor V2Ga5

We present a thorough investigation of the physical properties and superconductivity of the binary intermetallic ${\mathrm{V}}_2{\mathrm{Ga}}_5$. Electrical resistivity and specific heat measurements show that ${\mathrm{V}}_2{\mathrm{Ga}}_5$ enters its superconducting state below $T_{sc}=$ 3.5 K, with a critical field of $H_{\mathrm{c}2,\perp \mathrm{c}}\left(H_{\mathrm{c}2,\left|\right|\mathrm{c}}\right)=6.5\left(4.1\right)$ kOe. With $H\perp c$, the peak effect was observed in resistivity measurements, indicating the ultrahigh quality of the single crystal studied. The resistivity measurements under high pressure reveal that the $T_{sc}$ is suppressed linearly with pressure and reaches absolute zero around 20 GPa. Specific heat and muon spin relaxation measurements indicate that the two-gap $s$-wave model best describes the superconductivity of ${\mathrm{V}}_2{\mathrm{Ga}}_5$. The bands near the Fermi level around the $Z$ and $\mathrm{\Gamma }$ points are observed and analyzed by the angle-resolved photoemission spectroscopy measurements and first-principles band structure calculations. We therefore conclude that ${\mathrm{V}}_2{\mathrm{Ga}}_5$ is a phonon-mediated two-gap $s$-wave superconductor.