We report a $\mu \text{SR}$ study of ${\text{LiCrO}}_2$, which has a magnetic lattice made up of a stacking of triangular Heisenberg antiferromagnetic (${\text{Cr}}^{3+}$, $S=3/2$) layers. A static magnetically ordered state is observed below the transition temperature $T_N=62\text{K}$, while the expected peak of the relaxation rate is slightly shifted downward by a few kelvins below $T_N$. We draw a comparison with the isostructural compound ${\text{NaCrO}}_2$, where an exotic broad fluctuating regime has been observed [A. Olariu, P. Mendels, F. Bert, B. G. Ueland, P. Schiffer, R. F. Berger, and R. J. Cava, Phys. Rev. Lett. 97, 167203 (2006)] and was suggested to originate from topological excitations of the triangular lattice. Replacing Na by Li strongly narrows the exotic fluctuating regime formerly observed in ${\text{NaCrO}}_2$, which we attribute to a more pronounced interplane coupling in ${\text{LiCrO}}_2$.

• Received 18 February 2009

DOI:https://doi.org/10.1103/PhysRevB.79.224401