Static magnetic order on the triangular lattice in with

Abstract

Abstract In spite of numerous experimental and theoretical reports on LiNiO 2 , due to fundamental interest because its Ni 3 + ions form a triangular S = 1 2 two-dimensional lattice, no consistent picture has emerged of the nature of its ground state. We have investigated the Li x NiO 2 system ( 0.1 ⩽ x ⩽ 1 ) using muon-spin spectroscopy to gain further insight from the effects of varying the spin concentration. Static magnetic order, most likely to be incommensurate to the spatial lattice period, was found for x ⩾ 0.6 , while disordered magnetism due to localized Ni moments appears for x = 1 2 - 1 4 , and, finally, Li 0.1 NiO 2 exhibits almost fully non-magnetic behavior. Combining the result of susceptibility measurements, the ground state of LiNiO 2 is thought to be a “static but short-range” A-type antiferromagnetic ordered system. That is, the Ni 3 + moments align ferromagnetically along the c-axis in the NiO 2 plane with an incommensurate modulation probably due to canting of the Ni 3 + moments, but antiferromagnetically between the adjacent NiO 2 planes.