Topological nodal-line semimetals (TNLSMs) are materials whose conduction and valence bands cross each other, meeting a topologically protected closed loop rather than discrete points in the Brillouin zone (BZ). The anticipated properties for TNLSMs, include drumhead-like nearly flat surface states, unique Landau energy levels, special collective modes, long-range Coulomb interactions, or the possibility of realizing high-temperature superconductivity. Recently, SrAs₃ has been theoretically proposed and then experimentally confirmed to be a TNLSM. Here, we report high-pressure experiments on SrAs₃, identifying a Lifshitz transition below 1 GPa and a superconducting transition accompanied by a structural phase transition above 20 GPa. A topological crystalline insulator (TCI) state is revealed by means of density functional theory (DFT) calculations on the emergent high-pressure phase. As the counterpart of topological insulators, TCIs possess metallic boundary states protected by crystal symmetry, rather than time reversal. In consideration of topological surface states (TSSs) and helical spin texture observed in the high-pressure state of SrAs₃, the superconducting state may be induced in the surface states, and is most likely topologically nontrivial, making pressurized SrAs₃ a strong candidate for topological superconductor.

拓扑节点线半金属（TNLSM）是其导带和价带彼此交叉的材料，在布里渊区（BZ）中遇到受拓扑保护的闭环而不是离散点。TNLSM的预期特性包括鼓面状的近乎平坦的表面状态，独特的Landau能级，特殊的集体模态，长距离库仑相互作用或实现高温超导性的可能性。最近，从理论上提出了SrAs ₃，然后在实验上证实它是TNLSM。在这里，我们报告了有关SrAs ₃的高压实验，确定了低于1 GPa的Lifshitz跃迁和伴随高于20 GPa的结构相变的超导转变。借助密度泛函理论（DFT）对出现的高压相进行计算，揭示了拓扑晶体绝缘体（TCI）的状态。作为拓扑绝缘体的对应物，TCI具有受晶体对称性保护的金属边界态，而不是时间反转。考虑到在SrAs ₃的高压状态下观察到的拓扑表面状态（TSSs）和螺旋自旋织构，超导状态可能在表面状态下诱发，并且很可能在拓扑上是无关紧要的，从而使加压SrAs ₃成为用于SrAs ₃的强候选者。拓扑超导体。