Three‐Dimensional Dirac Semimetal β ‐PbO 2

Based on first‐principles calculation, we found a new type of three‐dimensional (3D) topological semimetal: β ‐PbO 2 . When spin–orbit coupling (SOC) is ignored, β ‐PbO 2 behaves as a node‐line semimetal, but in the presence of SOC, the system turns into 3D Dirac semimetal, and the Dirac points are protected by C 4 crystal symmetry. Moreover, the surface states and Fermi arcs on the semi‐infinite edge clearly reveal its topological nature. Therefore, β ‐PbO 2 provides a flexible platform for exploring exotic physical phenomena of Dirac semimetals.