Unraveling the Robust Superconductivity Phenomenon of High-Entropy Alloy under Pressure*

Recent experiments demonstrate a “robust superconductivity phenomenon” in niobium-based alloys, where the superconducting state remains intact and the critical temperature (T_c) remains unaffected by external pressure well above tens of gigapascals (GPa) into the megabar regime. Motivated by these observations, we perform ab initio calculations for body-centered cubic Nb and NbTi crystals, as well as for special quasi-random structures of Nb_0.5Ti_0.5 and (NbTa)_0.7(HfZrTi)_0.3 high-entropy alloy (HEA). The results unravel the underlying mechanism of robust superconductivity, stemming from a compensation effect between varying electronic and phonon properties under pressure. The calculations also reveal how both structural and chemical disorders modify the superconducting state in these systems. The first-principles T_c values achieve quantitative agreement with experimental results throughout the entire pressure range. Our study paves the way for exploring superconducting HEAs under pressure via advanced first-principles simulations.