Effects of magnetic ordering on the band structure of Dirac semimetal EuAl4

Topological Dirac semimetals in the BaAl4-type structure, including EuAl4, were predicted to host interesting behaviors such as charge density wave (CDW), magnetically ordered phases, and topological spin textures. Early studies of EuAl4 have shown presence of CDW alongside several antiferromagnetically (AFM) ordered phases at low temperatures. Here, we investigate the electronic properties of this interesting material using ARPES and DFT calculations. We observe significant changes in the band structure upon each of the four consecutive AFM transitions including band splitting, renormalizations, and the appearance of new bands forming additional Fermi sheets. We also found significant enhancement of the quasiparticles' lifetime due to suppression of spin flip scattering. We observe that most significant changes in electronic properties occur not at Neel temperature but rather at the AFM3 to AFM4 transition, which coincides with the largest drop in resistivity and the spontaneous reversal of spin chirality.