Electronic Structures of Ferromagnetic CeAgSb${}_2$:Soft X-ray Absorption, Magnetic Circular Dichroism and Angle-Resolved Photoemission Spectroscopies

We report a combined study for the electronic structures of ferromagnetic CeAgSb${}_2$ using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce $M_{4, 5}$ XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce $4f$ electrons. The linear dichroism effects in the Ce $M_{4,5}$ XAS spectra demonstrate the ground state Ce $4f$ symmetry of $\mathrm{\Gamma }{}_6$, the spatial distribution of which is directed along the $c$-axis. The XMCD results give support to the picture of local-moment magnetism in CeAgSb${}_2$. Moreover it is also found that the theoretical band dispersions for LaAgSb${}_2$ provides better description of the ARPES band structures than those for CeAgSb${}_2$. Nevertheless, ARPES spectra at the Ce $3d$-$4f$ resonance show the momentum dependence for the intensity ratio between Ce $4f_{5\mathrm{/}2}^1$ and $4f_{7\mathrm{/}2}^1$ peaks in a part of the Brillouin zone, suggesting the non-negligible momentum dependent hybridization effect between the Ce $4f$ and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb${}_2$.