Unconventional superconductivity in UAs₂ under pressure

The recently found spin-triplet superconductor candidate UTe₂ has attracted enormous attention. Here, we report the finding of superconductivity up to T_c ≈ 4 K in one of its siblings, i.e., UAs₂ under pressure. UAs₂ shows metallic behavior with an antiferromagnetic transition at about 274 K at ambient pressure. Upon applying pressure, this transition is pushed down to lower temperatures with improved electric conductivity. When the pressure rises beyond about 20 GPa, superconductivity occurs together with the emergence of a linear temperature dependence of normal state resistance in low-temperature region. The superconductivity with the highest onset T_c ≈ 4.05 K is reached under a pressure of 26.8 GPa, and it is robust against magnetic field with the μ₀H_c2(0) ~ 12 T, far beyond the Pauli limit. Higher pressures will suppress the superconductivity and bring back the Fermi liquid behavior. Our results open an avenue for investigating the unconventional superconductivity concerning the mysterious 5f-band electrons in uranium (U)-based system.