Novel surface state in GdBi and DyBi induced by long-range magnetic order*

Several rare-earth monopnictides, including GdBi, were predicted to host topologically nontrivial states. Earlier ARPES studies of GdBi in the paramagnetic phase confirmed the presence of Dirac states in the corner of the Brillouin zone. Also, several recent ARPES studies reported the development of unconventional surface states in several rare-earth monopnictides (NdBi, NdSb, CeBi) in the antiferromagnetic phase, which form spin textured Fermi arcs and unusual magnetic splitting. Here, we investigate the evolution of the electronic structure of GdBi and DyBi upon antiferromagnetic transition using Angle-resolved photoemission spectroscopy. These materials are known to be magnetically ordered along (111) direction, which is different from the direction of magnetic ordering in NdBi, NdSb, CeBi. We observed the emergence of additional states in the electronic structure of GdBi and DyBi in the antiferromagnetic phase, including Dirac-like dispersions. These new states are different from those previously observed in other rare-earth monopnictides.