Magnetic ground state of KCr3As3

Many unconventional superconductors, such as cuprates and iron-based materials, display spin-glass states in the underdoped regime, which usually coexist and/or compete with unconventional superconductivity. Here, we performed zero-field (ZF) and longitudinal-field (LF) muon spin-rotation experiments ($\ensuremath{\mu}\mathrm{SR}$) on quasi-one-dimensional ${\mathrm{KCr}}_{3}{\mathrm{As}}_{3}$. Our ZF $\ensuremath{\mu}\mathrm{SR}$ measurements reveal a large decrease (about 1/3) in the initial asymmetry below 10 K, indicating the presence of a magnetic phase transition. The analysis of the LF $\ensuremath{\mu}\mathrm{SR}$ results illustrates this transition at the same temperature, and points it to a spin-glassy state. These results would, potentially, confirm unconventional superconductivity in K-Cr-As and related compounds.