Evolution of Fermi-Arc Surface States in a Magnetic-Field Induced Weyl Semimetal

Weyl semimetals (WSMs) have a three-dimensional (3D) bulk band structure in which the conduction and valence bands meet at discrete points, i.e. Weyl points. Projections of Weyl points with opposite chirality are connected by Fermi arcs at a surface. Topological Dirac semimetals (DSMs) have 3D Dirac points which can be viewed as two superimposed copies of Weyl points stabilized by rotational symmetry. When an external magnetic field is applied to a DSM, Dirac points can be separated into multiple Weyl points and so a WSM phase can be driven. DSMs and WSMs have received a lot of attention because they exhibit the chiral anomaly and novel magneto-transport signatures. We develop a tight-binding model based on Wannier functions directly from density functional theory (DFT) calculations for a topological DSM. We add spin-orbit coupling and Zeeman splitting terms in the tight-binding model. We find that each Dirac node splits into two single Weyl points with linear dispersion and two double Weyl points with quadratic dispersion. Our calculations also reveal interesting evolution of Fermi-arc surface states and other topological surface states as a function of chemical potential in the presence of the external magnetic field.