Materials in the family $R$V$_{ 6}$Sn$_{ 6}$ ($R=$ rare earth) provide a unique platform to investigate the interplay between local moments from $R$ layers and nonmagnetic vanadium kagome layers. Yet, the investigation of actinide members remains scarce. Here we report the synthesis of UV$_{ 6}$Sn$_{ 6}$ single crystals through the self-flux technique. Magnetic susceptibility, specific heat, electrical resistivity, and thermal expansion measurements reveal two uranium-driven antiferromagnetic transitions at $T_{ N1}=29$~K and $T_{ N2}=24$~K, a complex field-temperature phase diagram, and unusual negative domain wall magnetoresistance. Specific heat measurements unveil a modest Sommerfeld coefficient of $\gamma = 40$~mJ/mol.K$^{ 2}$, consistent with angle-resolved photoemission spectroscopy measurements that show a moderate $f$-electron enhancement at the Fermi level ($E_{ F}$). Our experiments support a modest contribution from \textit{ 5f} flat bands to the density of states at $E_{ F}$, whereas our band structure calculations place the vanadium flat bands 0.25~eV above $E_{ F}$. Our findings point to a materials opportunity to expand the uranium 166 family with the goal of enhancing correlations by tuning $5f$ and $3d$ flat bands to $E_{ F}$.
Categories: cond-mat.str-el cond-mat.mtrl-sci