Simultaneous Superconducting\nand Topological Properties\nin Mg–Li Electrides at High Pressures

Electrides\nas a unique class of emerging materials exhibit fascinating\nproperties and hold important significance for understanding matter\nunder extreme conditions, which is characterized by valence electrons\nlocalized into the interstitial space as quasi-atoms (ISQs). In this\nwork, using crystal structure prediction and first-principles calculations,\nwe identified seven stable phases of Mg–Li that are electrides\nwith novel electronic properties under high pressures. Among them,\nMgLi<sub>10</sub> is a semiconductor with a band gap of 0.22 eV, and <i>Pm-</i>3<i>m</i> MgLi is a superconductor with a superconducting\ntransition temperature of 22.8 K. The important role played by the\nlocalization degree of ISQs in the superconducting transition temperature\nof these electrides is revealed by systematic comparison of Mg–Li\nwith other Li-rich electride superconductors. Furthermore, we proved\nthat <i>Pm-</i>3<i>m</i> MgLi and <i>Pnma</i> MgLi also have distinct topological behavior with metallic surface\nstates and the nonzero <i>Z</i><sub>2</sub> invariant. The\nsimultaneous coexistence of superconductivity, electronic band topology,\nand electride property in the same structure of <i>Pm-</i>3<i>m</i> MgLi and <i>Pnma</i> MgLi demonstrates\nthe feasibility of realizing multiquantum phases in a single material,\nwhich will stimulate further research in these interdisciplinary fields.