material systems with heavy 4d/5d transition metal compounds [@doi:10.1146/annurev-conmatphys-020911-125138]. The iridates deserve special mention in this category and have been instrumental in exploring much of this uncharted territory [@schaffer2015recent; @rau2015spin].

In addition to the emergence of topologically non-trivial ground states, the interplay between SOC and magnetic degrees of freedom themselves is also quite interesting. The family of AMnBi$_2$(A = Sr, Ca) compounds are particularly important in this context. Being structurally similar to iron based superconductors, they are referred to as manganese pnictides, which contain layers of Mn-Bi edge sharing tetrahedra and a Bi square net separated by a layer of A atoms [@guo2014coupling]. These compounds were expected from first principles DFT band calculations to host highly anisotropic Dirac dispersions with a finite gap at the Dirac point due to SOC [@lee2013anisotropic]. Such predictions were confirmed experimentally through magnetization, magneto-transport measurements [@park2011anisotropic; @wang2012two] and later using angle resolved photoemission spectroscopy (ARPES) [@feng2013strong]. What makes these compounds particularly interesting is the antiferromagnetic (AFM) ordering of the spin magnetic moment on the Mn$^{2+}$ atoms which has a $3d^5$ electronic configuration. The magnitude of the ordered moment is around $4\mu_B$ with an ordering temperature $\sim$300K as observed in several experiments [@lee2013anisotropic; @guo2014coupling]. Strong in-plane 