Neutron scattering and mu SR investigations of quasi-one-dimensional magnetism in the spin=3/2 compound Li3RuO4

Article

关键词: TOTAL-ENERGY CALCULATIONS;    WAVE BASIS-SET;    HEISENBERG-ANTIFERROMAGNET;    EXCHANGE INTERACTIONS;    TRIANGULAR LATTICE;    ANTI-FERROMAGNET;    DYNAMICS;    CHAIN;    CRYSTAL;    LIQUID;   

DOI  :  10.1103/PhysRevB.84.174430

来源: SCIE

【 摘 要 】

The S = 3/2, quasi-one-dimensional (1D) zig-zag chain Heisenberg antiferromagnet Li3RuO4 has been investigated using heat capacity, inelastic neutron scattering, neutron diffraction, and mu SR measurements on a powder sample. Our neutron diffraction and mu SR studies confirm a long-range ordering of the magnetic moments on the Ru5+ cations below 40 K. The magnetic excitations were measured at various temperatures above and below the three-dimensional (3D) ordering temperature in order to understand the broad peak observed in the temperature dependence of the magnetic susceptibility. At 5 K we have observed two well-defined magnetic excitations at 5.5 meV and 8.5 meV and a weak low-energy peak near similar to 2 meV. We interpret the 5.5 meV energy peak as a 1D zone-boundary mode and that at 8.5 meV as arising from a maximum away from the zone boundary in the dispersion curve for spin-wave modes along the chain of Ru5+ ions. The weaker peak near 2 meV is thought to arise from a weak interchain coupling. Our data are best reproduced using a model with three intrachain interactions and one weak interchain interaction. The experimental spin-exchange interactions are in good agreement with those calculated for a 1D model by density functional theory (DFT) methods. Furthermore, above T-N we observe strong diffuse scattering at the same Q-position as the 5.5 meV mode, which suggests the presence of short-range magnetic correlations above TN. We have estimated the correlation length xi similar to 2.9 angstrom at 50 K, which is close to 2.99 angstrom, the shortest distance between the Ru5+ cations along the zig-zag chain.

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