Electronic structure of antiferromagnetic Dirac semimetal candidate GdIn3

Recently, magnetic topological quantum materials have attracted substantial research attention due to their great application potential. Here, using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation, we systematically investigate the electronic structure of antiferromagnet Dirac semimetal candidate $\mathrm{Gd}{\mathrm{In}}_{3}$. According to our ab initio calculation, there exist two and one pair(s) of Dirac fermions in the paramagnetic and antiferromagnetic state, respectively. In the antiferromagnetic state, the magnetic Dirac semimetal phase is protected by ${C}_{4z}$ rotation symmetry in the type-IV magnetic space group. Our experiment above the N\'eel temperature is well reproduced by the calculated band structure in the paramagnetic state, from which we identify a pair of Dirac fermions at 1.5 eV below the Fermi level. However, we do not observe the signature of electronic reconstruction in the antiferromagnetic state, suggesting a weak interaction between the localized Gd $4f$ states of spin configuration $S=7/2{\ensuremath{\mu}}_{\mathrm{B}}$ and the itinerant conduction electrons. Our results confirm the Dirac semimetal nature of the paramagnetic $\mathrm{Gd}{\mathrm{In}}_{3}$ and provide important insights into its antiferromagnetic Dirac semimetal phase.