No observation of chiral flux current in the topological kagome metal CsV$_{3}$Sb$_{5}$

TL;DR

This study used spin-polarized scanning tunneling microscopy to search for chiral flux currents in CsV$_{3}$Sb$_{5}$ but found no evidence of such currents within experimental limits, despite observing charge density wave orders.

Contribution

The paper provides the first direct experimental search for chiral flux currents in CsV$_{3}$Sb$_{5}$ using refined spin-polarized STM techniques, setting upper bounds on possible magnetic moments.

Findings

No detectable chiral flux current phase within experimental accuracy.

Charge density wave and stripe orders observed.

No local magnetic moments detected, constraining chiral current magnitude.

Abstract

Compounds with kagome lattice usually host many exotic quantum states, including the quantum spin liquid, non-trivial topological Dirac bands and a strongly renormalized flat band, etc. Recently an interesting vanadium based kagome family $A$V$_{3}$Sb$_{5}$ ($A$ = K, Rb, or Cs) was discovered, and these materials exhibit multiple interesting properties, including unconventional saddle-point driving charge density wave (CDW) state, superconductivity, etc. Furthermore, some experiments show anomalous Hall effect which inspires that there might be some chiral flux current states. Here we report scanning tunneling measurements by using spin-polarized tips. Although we have observed clearly the $2a_0\times2a_0$ CDW and $4a_0$ stripe orders, the well-designed experiments with refined spin-polarized tips do not reveal any trace of the chiral flux current phase in CsV$_3$Sb$_5$ within the limits of experimental accuracy. No observation of the local magnetic moment in our experiments may put an upper bound constraint on the magnitude of magnetic moments induced by the possible chiral loop current which has a time-reversal symmetry breaking along $c$-axis in CsV$_{3}$Sb$_{5}$.