Topological phase transition in layered XIn2P2 (X = Ca, Sr)

Based on fully relativistic first-principles calculations, we studied the topological properties of layered XIn2P2 (X = Ca, Sr). Band inversion can be induced by strain without SOC, forming one nodal ring in the k(z) = 0 plane, which is protected by the coexistence of time reversal and glide mirror symmetries. Including SOC, a substantial band gap is opened along the nodal line and the line-node semimetal would evolve into a topological insulator. These results reveal a category of materials showing quantum phase transition from trivial semiconductors and topologically nontrivial insulators by tuneable elastic strain engineering. Our investigations provide a new perspective about the formation of topological line-node semimetal under stain.