One-dimensional magnetic fluctuations in the spin-2 triangular lattice \alpha-NaMnO2

The S=2 anisotropic triangular lattice alpha-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 (Delta ~ 7.5 meV) has been analysed by the single-mode approximation. Exce...

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Bibliographic Details
Published inarXiv.org
Main Authors Stock, C, Chapon, L C, Adamopoulos, O, Lappas, A, Giot, M, Taylor, J W, Green, M A, Brown, C M, Radaelli, P G
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 04.07.2009
Subjects
Antiferromagnetism
Exchanging
Inelastic scattering
Magnetic anisotropy
Magnetic variations
Physics - Materials Science
Physics - Strongly Correlated Electrons
Spin dynamics
Topology
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Summary:The S=2 anisotropic triangular lattice alpha-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 (Delta ~ 7.5 meV) has been analysed by the single-mode approximation. Excellent agreement with the experiment is achieved when a dominant exchange interaction (|J|/k_B ~ 73 K), along the monoclinic b-axis and a sizeable easy-axis magnetic anisotropy (|D|/k_B ~ 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. alpha-NaMnO2 therefore represents a model system where the geometric frustration is resolved through the lowering of the dimensionality of the spin interactions.
ISSN:2331-8422
DOI:10.48550/arxiv.0907.0742