The magnetic nature of a metallic two-dimensional triangular compound, ${\mathrm{CrSe}}_2$, has been investigated by muon spin rotation and relaxation ($\mu {}^{+}\mathrm{SR}$) measurements using both powder and single crystal samples. It is found that ${\mathrm{CrSe}}_2$ enters into a static antiferromagnetic (AF) ordered state below 157 K ($=T_{\mathrm{N}}$). Furthermore, the AF state is slightly changed below around 20 K ($=T_{\mathrm{N}2}$). Based on the analysis of the internal magnetic fields at the muon sites predicted with DFT calculations, collinear AF and helical ${120}^{\circ }$ AF are clearly eliminated for the ground state of ${\mathrm{CrSe}}_2$. The most probable one is an incommensurate spin density wave order.

• Received 8 May 2016
• Revised 14 June 2016

DOI:https://doi.org/10.1103/PhysRevB.94.014408