Magnetic structure for NaCr2O4 analyzed by neutron diffraction and muon spin-rotation

We have investigated the magnetic ground state of a novel one-dimensional compound, ${\text{NaCr}}_2{O}_4$, in which ${\text{Cr}}_2{O}_4$ double chains, i.e. zig-zag chains are aligned parallel to the $b$-axis, by means of both muon-spin rotation and relaxation (${\mu }^{+}$SR) and neutron diffraction (ND) measurements. The ${\mu }^{+}$SR results reveal the formation of static antiferromagnetic order below Néel temperature ($T_N=124\text{K}$). The ND measurements also demonstrate the appearance of magnetic Bragg peaks with the propagation vector $\overrightarrow{k}=\left(\mathrm{1,\; 0,\; 1}\right)$ below $T_N$. Combined analyses of the ${\mu }^{+}$SR and ND data clarify that the Cr moments in each zig-zag chain are aligned ferromagnetically along the $c$-axis, whereas antiferromagnetically along the $a$-axis between the adjacent zig-zag chains.