Fig. 4: HOFA states in α″-Cd3As2 and KMgBi.
From: Strong and fragile topological Dirac semimetals with higher-order Fermi arcs
a Bulk bands incorporating the effects of SOC of α″-Cd3As2 in SG 137 (\( P{4}_{2}/nmc1^{\prime} \))10,18,20,56,57. This semimetal exhibits \( {\mathcal{T}} \)-reversed pairs of bulk 3D Dirac cones as well as 2D TI cones on its faces as a consequence of the nontrivial \( {{\mathbb{Z}}}_{2} \) topology of the kz = 0 plane (Supplementary Note 13)10,18,19,20. c The hinge spectrum of the k ⋅ p model of α″-Cd3As2 introduced in ref. 18 exhibits previously undetected HOFA states connecting the projections of the bulk Dirac cones (white) to the hinge projection of the topological face cones (blue). b Bulk bands incorporating the effects of SOC and (d) hinge states of the candidate tilted Dirac semimetal KMgBi in SG 129 (\( P4/nmm1^{\prime} \))58,59. d Zooming into the green boxed region, HOFAs are clearly visible connecting the projections of the bulk, tilted 3D Dirac points (white) to the projections of surface 2D TI cones (blue). The bulk band structures in (a) and (b) were obtained from first-principles, and then used to fit tight-binding models whose hinge Green's functions are shown in (c) and (d), respectively (Supplementary Note 13).
