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

TL;DR

This study reports the successful growth of single crystals of K$_2$Cr$_3$As$_3$, measures its magnetic properties, and confirms it as a spin-triplet superconductor through hyperfine coupling analysis.

Contribution

It provides the first direct determination of hyperfine coupling constants and orbital contributions in K$_2$Cr$_3$As$_3$, supporting its classification as a spin-triplet superconductor.

Findings

Superconducting transition temperature $T_c$=6.2 K.

Hyperfine coupling constants determined from Knight shift and susceptibility.

Orbital contribution $K_{orb}$ consistent with previous estimates.

Abstract

We report single crystal growth of strongly-correlated compound K$_2$Cr$_3$As$_3$ with superconducting temperature $T_{\textrm c}$=6.2 K, and the measurements of magnetic susceptibility $\chi$ above $T_{\textrm c}$. 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 $K_{\textrm{orb}}$. Our results of $K_{\textrm{orb}}$ 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.