Hidden magnetism uncovered in a charge ordered bilayer kagome material ScV6Sn6

Abstract

Charge ordered kagome lattices have been demonstrated to be intriguing platforms for studying the intertwining of topology, correlation, and magnetism. The recently discovered charge ordered kagome material ScV6Sn6 does not feature a magnetic groundstate or excitations, thus it is often regarded as a conventional paramagnet. Here, using advanced muon-spin rotation spectroscopy, we uncover an unexpected hidden magnetism of the charge order. We observe an enhancement of the internal field width sensed by the muon ensemble, which takes place within the charge ordered state. More importantly, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. Taken together with the hidden magnetism found in AV3Sb5 (A = K, Rb, Cs) and FeGe kagome systems, our results suggest ubiqitous time-reversal symmetry-breaking in charge ordered kagome lattices.

Quantum oscillations evidence for topological bands in kagome metal ScV6Sn6

“…Figure 1(b) displays the magnetoresistance of ρ xx when the magnetic field H is applied in the ab-plane under different T. These magnetoresistance (MR) curves exhibit subquadratic or nearly linear behavior. This linear MR feature also reported recently in [33,34] could indicate an unconventional phase, such as the formation of a pseudogap as claimed in [33]. The main feature in figure 1(b) is the clear SdH oscillations when H > 3.5 T, and the amplitude decreases with increasing T. The transverse resistivity ρ xy has also been measured at T = 1.8 K when the field is along the c axis as shown in figure 1(b) inset.…”

Tuning charge density wave of kagome metal ScV6Sn6

“…To understand the origin of the Hall resistivity in the Cr-substituted sample, we compare it with the pristine ScV 6 Sn 6 sample. Previous reports on pristine crystal [30,31] have shown anomalous Hall effect (AHE)-like behavior in the Hall resistivity, which may be due to the formation of a loop current in the V kagome lattice, breaking the time reversal symmetry (TRS) [17,27]. However, substitution of the Cr atoms in the V site of the kagome lattice destroys the V-V bonds by inducing disorder.…”

“…Furthermore, ScV 6 Sn 6 exhibits an anomalous Hall-like behavior [30,31], which cannot be explained by a multiple band model. Instead, it suggests a hidden magnetism origin [27]. Interestingly, this anomalous Hall-like feature coexists with the CDW phase and dies down above the T CDW .…”

“…The out-of-plane lattice dynamics of the CDW suggests an unconventional nature [10]. Additionally, the CDW exhibits various microscopic features, such as the critical role of phonons [20][21][22][23], substantial spin Berry curvature [24], partial bandgap opening [25,26], and hidden magnetism [27]. It is worth noting that the CDW phase of ScV 6 Sn 6 is very fragile without any additional features of superconductivity and magnetism.…”

Pressure-Tuned Intrinsic Anomalous Hall Conductivity in Kagome Magnets RV6Sn6 (R = Gd, Tb)

“…ScV6Sn6 undergoes an electron-phonon interaction driven CDW phase transition, indicating that the electronic instability from the V kagome lattice in ScV6Sn6 just plays a marginal role. [40][41][42][43][44][45][46][47][48] YbV6Sn6 formed by Ybbased triangular Kondo lattice features the quantum criticality near 0 K and an unexpected magnetic ordering below 0.4 K. [49] Notably, recent theoretical calculations and angle resolved photoemission spectroscopy measurements † These authors contributed equally to this work. reveal that HoV6Sn6, GdV6Sn6, and TbV6Sn6 are 𝑍2 kagome metals with tunable multiple van Hove singularities and topological Dirac surface states.…”