Topologically nontrivial type-I and type-II nodal-line states in magnetic configurations of square-net pnictide CeCuBi2

We use first-principles calculations to demonstrate that CeCuBi2 contains topologically nontrivial type-I and type-II nodal degeneracies, the former in the antiferromagnetic configuration and the latter in the ferromagnetic configuration. Furthermore, we analyze the effect of magnetic ordering on the location of the nodal line and observe how the change from antiferromagnetic to ferromagnetic ordering shifts nodal line states up to the Fermi level. Our results demonstrate the possibility of accessing multiple topological states through changes in magnetic order, opening up new possibilities for magnetic-order tuned topological spintronics.