Superconductivity and phase diagram in the nanostructured eutectic Ga–Ag alloy

Here, we present a study of superconductivity in the Ga–Ag alloy embedded into porous template with pore diameter of 10 nm. The composition was close to the eutectic point in the gallium-rich range. We measured DC and AC magnetizations for temperatures from 1.8 to 10 K and magnetic fields up to 6 T. Three superconducting transitions were found at temperatures 7.05, 6.08, and 2.65 K in contrast to the bulk counterpart. Upper critical field lines were obtained. Activation barriers were evaluated from the AC data. The temperatures of the superconducting transitions were ascribed to emergence of $\beta$- and $t$-Ga and of an intermetallic different from bulk Ag$_3$Ga$_2$.