One-Dimensional Magnetic Fluctuations in the Spin-2 Triangular Lattice α-NaMnO2

Christopher Stock, Laurent C Chapon, O Adamopoulos, A Lappas, M Giot, J Taylor, M Green, C Brown, P Radaelli

Research output: Contribution to journalArticlepeer-review

Abstract

The S=2 anisotropic triangular lattice α-NaMnO2 is studied by neutron inelastic scattering. Antiferromagnetic order occurs at T≤45  K with opening of a spin gap. The spectral weight of the magnetic dynamics above the gap (Δ≃7.5  meV) has been analyzed by the single-mode approximation. Excellent agreement with the experiment is achieved when a dominant exchange interaction (|J|/kB≃73  K), along the monoclinic b axis and a sizable easy-axis magnetic anisotropy (|D|/kB≃3  K) are considered. Despite earlier suggestions for two-dimensional spin interactions, the dynamics illustrate strongly coupled antiferromagnetic S=2 chains and cancellation of the interchain exchange due to the lattice topology. α-NaMnO2 therefore represents a model system where the geometric frustration is resolved through the lowering of the dimensionality of the spin interactions.
Original languageEnglish
Article number077202
Number of pages4
JournalPhysical Review Letters
Volume103
Issue number7
DOIs
Publication statusPublished - 11 Aug 2009

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