Orbital magnetization in the Nb-substituted Kagome metal CsV$_3$Sb$_5$

TL;DR

This paper investigates how Nb substitution in CsV3Sb5 enhances orbital magnetization and modifies electronic structure, revealing increased magnetic circular dichroism linked to orbital moments and van Hove singularities.

Contribution

It provides the first detailed analysis of how Nb doping affects orbital magnetic moments and electronic structure in CsV3Sb5 using angle-resolved photoemission spectroscopy.

Findings

Nb doping increases band width and gap opening at Dirac crossings.

Enhanced magnetic circular dichroism signal due to Nb doping.

Orbital magnetic moments couple to van Hove singularities near the Fermi level.

Abstract

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 \blue{an increase of the band width} 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 (MCDAD) compared to CsV$_3$Sb$_5$, enabling detailed analysis of magnetic circular dichroism in several bands near the Fermi level. These results \blue{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 \blue{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.