Observation of Dirac state in DySb*

Extreme magnetoresistance (XMR), magnetic and structural phase transition, and possible non-trivial topological phases in the rare-earthmonopnictide family have recently invigorated intense research interest. Recent reports have experimentally revealed the presence of a Dirac-like semimetallic phases in some lighter rare earth monopnictide materials. Here we present a systematic ARPES study as well as first-principles calculations of DySb, a potential candidate for hosting a Dirac semi-metal phase. Our studies reveal two hole-like Fermi surface pockets present at the zone center (Gamma) point as well as two elliptical electron-pockets present in the zone corner (X) point of the Brillouin zone (BZ). Interestingly, Rashba-split states are observed at the (X) point of the BZ in a certain momentum direction, which is further supported by our first-principles calculations. A Dirac state is also observed at the (X) point of the BZ in the vicinity of the magnetic transition temperature. Our study opens a new direction to look for Dirac semi-metal states in other members of the rare earth monopnictide family.