In spite of numerous experimental and theoretical reports on ${\text{LiNiO}}_2$, no consistent picture has emerged of the nature of its ground state. We have investigated the ${\text{Li}}_x{\text{NiO}}_2$ system $\left(0.1\le x\le 1\right)$ by means of muon-spin spectroscopy and susceptibility to gain further insight from the effects of varying the magnetic ion concentration. Static magnetic order, most likely to be incommensurate to the spatial lattice period, was found for $x\ge 0.6$ at low temperatures $\left(T\right)$, while disordered magnetism due to localized Ni moments appears for $x=1/2–1/4$ and, finally, ${\text{Li}}_{0.1}{\text{NiO}}_2$ exhibits almost fully nonmagnetic behavior down to the lowest $T$ measured. The ground state of ${\text{LiNiO}}_2$ is inferred to be a “static but short-range” $A$-type antiferromagnetic ordered system, in which the ${\text{Ni}}^{3+}$ moments align ferromagnetically along the $c$ axis in the ${\text{NiO}}_2$ plane with an incommensurate modulation probably due to canting of the ${\text{Ni}}^{3+}$ moments, but align antiferromagnetically between adjacent ${\text{NiO}}_2$ planes.

• Received 14 July 2008

DOI:https://doi.org/10.1103/PhysRevB.78.144412