  As a special type of collinear antiferromagnetism (AFM), altermagnetism has
garnered significant research interest recently. Altermagnets exhibit broken
parity-time symmetry and zero net magnetization in real space, leading to
substantial band splitting in momentum space even in the absence of spin-orbit
coupling. Meanwhile, parity-time symmetry breaking always induce nontrivial
band topology such as Weyl nodes. While Weyl semimetal states and nodal lines
have been theoretically proposed in altermagnets, rare reports of experimental
observation have been made up to this point. Using ARPES and first-principles
calculations, we systematically studied the electronic structure of the
room-temperature altermagnet candidate CrSb. At generic locations in momentum
space, we clearly observed band spin splitting. Furthermore, we identified
discrete surface Fermi arcs on the (100) cleaved side surface close to the
Fermi level originating from bulk band topology. Our results imply that CrSb
contains interesting nontrivial topological Weyl physics, in addition to being
an excellent room temperature altermagnet.
