Universal sublinear resistivity in vanadium kagome materials hosting charge density waves

The recent discovery of a charge density (CDW) state in ScV_6Sn_6 at T_CDW = 91 K offers new opportunities to understand the origins of electronic instabilities in topological kagome systems. By comparing to the isostructural non-CDW compound LuV_6Sn_6, we unravel interesting electrical transport properties in ScV_6Sn_6, above and below the charge ordering temperature. We observed that by applying a magnetic field along the a axis, the temperature behavior of the longitudinal resistivity in ScV_6Sn_6 changes from metal-like to insulator-like above the CDW transition. We show that in the charge ordered state ScV_6Sn_6 follows the Fermi liquid behavior while above that, it transforms into a non-Fermi liquid phase in which the resistivity varies sublinearly over a broad temperature range. The sublinear resistivity, which scales by T^3/5 is a common feature among other vanadium-containing kagome compounds exhibiting CDW states such as KV_3Sb_5, RbV_3Sb_5, and CsV_3Sb_5. By contrast, the non-Fermi liquid behavior does not occur in LuV_6Sn_6. We explain the T^3/5 universal scaling behavior from the Coulomb scattering between Dirac electrons and Van Hove singularities; common features in the electronic structure of kagome materials. Finally, we show anomalous Hall-like behavior in ScV_6Sn_6 below T_CDW, which is absent in the Lu compound. Comparing the transport properties of ScV_6Sn_6 and LuV_6Sn_6 is valuable to highlight the impacts of the unusual CDW in the Sc compound.