A New Dirac Semimetal in Hexagonal BaGaSnH

By first-principles calculations, we find that BaGaSnH is a topological Dirac semimetal with a pair of Dirac points at \((0,0, \pm 0.45\frac{2\pi }{c})\) when spin–orbit coupling (SOC) is considered. The Dirac points are exactly at the Fermi energy, which makes the experimental measurement easy. The Dirac semimetal state as well as the topological properties are sensitive to the strain, which makes the compound enter the trivial semiconductor state. The finding of a Dirac semimetal phase in BaGaSnH may stimulate further research on the topological properties of hexagonal materials and promote new practical applications.