Three‐Dimensional Dirac Semimetal β‐PbO2

Based on first‐principles calculation, we found a new type of three‐dimensional (3D) topological semimetal: β‐PbO2. When spin–orbit coupling (SOC) is ignored, β‐PbO2 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 C4 crystal symmetry. Moreover, the surface states and Fermi arcs on the semi‐infinite edge clearly reveal its topological nature. Therefore, β‐PbO2 provides a flexible platform for exploring exotic physical phenomena of Dirac semimetals.