Intertwined orders in the kagome metal systems from the Raman scattering perspective

The kagome lattice with corner shared triangle network is a fertile platform to study the exotic orders at the interplay between band topology and strong correlations. Various electronic orders such as charge and spin density wave order, charge bond order, chiral flux order, nematic order, and superconductivity are under rigorous investigation. Recently, vanadium-based kagome metal systems AV3Sb5 have aroused great interest in observing a giant anomalous Hall effect, chiral charge density order (CDW), and signatures of time-reversal symmetry-breaking without magnetic ordering. These systems are usually nonmagnetic and show weak electronic correlations. A strongly correlated version of AV3Sb5 is discovered in the hexagonal kagome metal FeGe which exhibits a CDW order coexisting with a collinear A-type antiferromagnetic (AFM) order. The CDW order in FeGe couples with the AFM order and can be tuned from short-range to long-range order by simple annealing at different temperatures.



In this talk, I will present our recent results about the intertwined orders in the CDW state of the kagome metal systems. We show the results of the interplay between multicomponent CDW orders in the kagome superconductor AV3Sb5 [1] and that the three-fold rotational symmetry is intact in AV3Sb5 [1]. In contrast, for the magnetic kagome FeGe system, we reveal that the three-fold rotational symmetry breaks at AFM transition with a lattice distortion on the order of 10^(-4), and the lattice symmetry tends to ascend in the spin canting phase [2]. We discuss the similarities and differences between the nonmagnetic AV3Sb5 and magnetic kagome metal FeGe systems from the Raman scattering, group-theoretical analysis, and the Landau free-energy model expansion perspectives. Finally, we present our new Raman results regarding the spectroscopic difference between annealed and as-grown FeGe samples.



Research at Rutgers was supported by the National Science Foundation (NSF) Grant No. DMR-2105001.



References

[1] Shangfei Wu et al, Phys. Rev. B 105,155106 (2022) Editors’ Suggestion

[2] Shangfei Wu et al, Phys. Rev. X 14, 011043 (2024)