Anomalous Hall effect and two-dimensional Fermi surfaces in the charge-density-wave state of kagome metal RbV3Sb5

AV _3 Sb _5 (A = Cs, K, Rb) is a recently discovered superconducting system ( $T_\mathrm{c}\sim0.9$ –2.5 K) in which the vanadium atoms adopt the kagome structure. Intriguingly, these systems enter a charge-density-wave (CDW) phase ( $T_\mathrm{CDW}\sim80$ –100 K), and further evidence shows that the time-reversal symmetry is broken in the CDW phase. Concurrently, the anomalous Hall effect (AHE) has been observed in KV _3 Sb _5 and CsV _3 Sb _5 inside the novel CDW phase. Here, we report a comprehensive study of a high-quality RbV _3 Sb _5 single crystal with magnetotransport measurements. Our data demonstrate the emergence of the AHE in RbV _3 Sb _5 when the CDW state develops. The magnitude of the anomalous Hall resistivity in the low temperature limit is comparable to the reported values in KV _3 Sb _5 and CsV _3 Sb _5 . The magnetoresistance channel further reveals a rich spectrum of quantum oscillation frequencies, many of which have not been reported before. In particular, a large quantum oscillation frequency (2235 T), which occupies ∼56% of the Brillouin zone area, was recorded. For the quantum oscillation frequencies with sufficient signal-to-noise ratio, we further perform field angle-dependent measurements, and our data indicate two-dimensional Fermi surfaces in RbV _3 Sb _5 . Our results provide indispensable information for understanding the AHE and band structure in kagome metal AV _3 Sb _5 .