Zeeman Splitting Induced Topological Nodal Structure in ZrTe₅

When time-reversal symmetry is broken by an external Zeeman field in a Dirac semimetal or small-gap insulator, rich nodal structures can be induced, including Weyl nodes or nodal lines. ZrTe₅ is known to be located near the phase boundary between strong and weak topological insulator, and recent experiments showed intriguing magnetic transport properties including anomalous Hall effect and the chiral magnetic effect. This indicates that Weyl nodes are developed in ZrTe₅ due to Zeeman splitting. However, a concrete theoretical study of the nodal structure of ZrTe₅ under Zeeman splitting covering the full Brillouin zone is still missing. We construct a Wannier-function based tight-binding model from first principles to investigate the effect of Zeeman splitting in ZrTe₅ and to fully explore the nodal structure near the Fermi level. We calculate the topological character of induced band crossings and examine the importance of magnetic field direction effect on the nodal structure.