Superconductivity of the Ga-Ag Eutectic Alloy Under Nanoconfinement

Gallium alloys are a major focus of modern research due to their applications in emerging fields such as microelectronics, soft robotics, wearable devices, and biotechnology. We present an investigation into the effects of nanoconfinement on superconductivity in a Ga-Ag alloy with a composition close to the eutectic point on the gallium-rich side. Magnetization measurements were carried out within a temperature range of 1.8 to 10 K for two nanocomposites based on synthetic opal and porous glass matrices loaded with Ga-Ag. Superconducting transitions were observed at temperatures significantly higher than the critical temperature of bulk gallium, allowing us to construct the corresponding superconducting phase diagrams. Furthermore, superconductivity was found to coexist with ferromagnetism, the appearance of which is ascribed to the interface between gallium and Ag3Ga2 segregates. The ferromagnetism induces a shift between the branches of the magnetization isotherms. Finally, a thermal hysteresis was observed between the temperature-dependent magnetization curves measured under field-cooled cooling (FCC) and field-cooled warming (FCW) protocols.