Fig. 1: Topological massive Dirac metal state in the antiferromagnetic state of EuAs₃, revealed by band calculations.

a Schematic for the crystal structure of EuAs₃ in the doubled magnetic unit cell. The arrows on Eu²⁺ represent the spin directions, which are parallel and antiparallel to the b axis. b Bulk and (110)-projected surface BZs of the doubled magnetic unit cell of EuAs₃ with several high-symmetry points marked. c Band structure of EuAs₃ from GGA + SOC + U (U = 5 eV) calculations for the AFM ground state. The inset shows the massive Dirac point with a small gap. d Fermi surfaces of EuAs₃ derived from the band structure. e Projected band structure of EuAs₃, where the symbol size represents the projected weight of Bloch states onto the As-p_x, p_y, and p_z orbitals as labeled. Band inversion can be observed at the Γ point. The Wannier charge center is calculated in the f k_z = 0 and g k_z = 0.5 planes. h Calculated surface states on the (010) surface. The nontrivial topological surface states are clearly visible.