Single crystal growth of and hyperfine couplings in the spin-triplet superconductor K${}_2$Cr${}_3$As${}_3$

We report single crystal growth of strongly-correlated compound K${}_2$Cr${}_3$As${}_3$ with superconducting temperature $T_{\text{c}}$=6.2 K, and the measurements of magnetic susceptibility $\chi$ above $T_{\text{c}}$. We determined the hyperfine coupling constants directly from the relation between the Knight shift ($K$) and susceptibility ($K$-$\chi$ plot) and obtained the orbital contribution $K_{\text{orb}}$. Our results of $K_{\text{orb}}$ is in fairly good agreement with the previous estimate using a novel method, and reinforce the conclusion that K${}_2$Cr${}_3$As${}_3$ is a spin-triplet superconductor.