Scalar Chiral Spin-1/2 Order on Kagome Lattices in Nd3Sb3Mg2O14

We introduce $\mathrm{Nd_{3}Sb_{3}Mg_{2}O_{14}}$ with ideal kagome lattices of neodymium ions in ABC stacking. Thermodynamic measurements show a Curie-Weiss temperature of $\Theta_{CW}=-0.12~$K, a Nd$^{3+}$ spin-1/2 Kramers doublet ground state, and a second order phase transition at $T_N=0.56(2)~$K. Neutron scattering reveals non-coplanar scalar chiral ${\bf k} =0$ magnetic order with a correlation length exceeding 400 \AA = 55 $a$ and an ordered moment of $1.79(5)~\mu_B$. This order includes a canted ferromagnetic component perpendicular to the kagome planes favored by Dzyaloshinskii-Moriya interactions.