Quantum magnetisms in uniform triangular lattices Li₂AMo₃O₈ (A?=?In, Sc).

ABSTRACT: Molecular based spin-1/2 triangular lattice systems such as LiZn₂Mo₃O₈ have attracted research interest. Distortions, defects, and intersite disorder are suppressed in such molecular-based magnets, and intrinsic geometrical frustration gives rise to unconventional and unexpected ground states. Li₂AMo₃O₈ (A?=?In or Sc) is such a compound where spin-1/2 Mo₃O₁₃ clusters in place of Mo ions form the uniform triangular lattice. Their ground states are different according to the A site. Li₂InMo₃O₈ undergoes conventional 120° long-range magnetic order below T_N?=?12?K whereas isomorphic Li₂ScMo₃O₈ exhibits no long-range magnetic order down to 0.5?K. Here, we report exotic magnetisms in Li₂InMo₃O₈ and Li₂ScMo₃O₈ investigated by muon spin rotation (?SR) and inelastic neutron scattering (INS) spectroscopies using polycrystalline samples. Li₂InMo₃O₈ and Li₂ScMo₃O₈ show completely different behaviors observed in both ?SR and INS measurements, representing their different ground states. Li₂InMo₃O₈ exhibits spin wave excitation which is quantitatively described by the nearest neighbor anisotropic Heisenberg model based on the 120° spin structure. In contrast, Li₂ScMo₃O₈ undergoes short-range magnetic order below 4?K with quantum-spin-liquid-like magnetic fluctuations down to the base temperature. Origin of the different ground states is discussed in terms of anisotropies of crystal structures and magnetic interactions.

SUBMITTER: Iida K 

PROVIDER: S-EPMC6372599 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature