Orbital magnetization in the Nb-substituted kagome metal CsV$_{3}$Sb$_{5}$

This study uses angle-resolved photoemission spectroscopy to examine the low-temperature electronic structure of Cs⁢(V$_{0.95}$⁢Nb$_{0.05}$)$_3$⁢Sb$_5$, demonstrating that partially substituting V atoms with isoelectronic Nb atoms results in an increase of the bandwidth and enhanced gap opening at the Dirac-like crossings due to the resulting chemical pressure. This increases the magnetic circular dichroism signal in the angular distribution compared to CsV$_3$⁢Sb$_5$, enabling detailed analysis of magnetic circular dichroism in several bands near the Fermi level. These results substantiate the predicted coupling of orbital magnetic moments to three van Hove singularities near the Fermi level at 𝑀 points. Previous studies have observed that Nb doping lowers the charge density transition temperature and increases the critical temperature for superconductivity. This article demonstrates that Nb doping concomitantly increases the magnetic circular dichroism signal attributed to orbital moments.