Quadratic nodal point in a two-dimensional noncollinear antiferromagnet

Quadratic nodal point (QNP) in two dimensions has so far been reported only in nonmagnetic materials and in the absence of spin -orbit coupling. Here, by first -principles calculations and symmetry analysis, we predict stable QNP near Fermi level in a two-dimensional kagome metal -organic framework material, Cr3(HAB)2, which features noncollinear antiferromagnetic ordering and sizable spin -orbit coupling. Effective k center dot p and lattice models are constructed to capture such magnetic QNPs. Besides QNP, we find Cr3(HAB)2 also hosts six magnetic linear nodal points protected by mirror as well as C2zT symmetry. Properties associated to these nodal points, such as topological edge states and quantized optical absorbance, are discussed.