Unusual spin dynamics in the van der Waals antiferromagnet FeGa2S4

Abstract

Spin dynamics in the van der Waals antiferromagnet FeGa${}_2$S${}_4$ with triangular lattices are investigated using magnetometry, neutron scattering, and muon spin relaxation measurements. The characteristic spin relaxation time is thoroughly clarified over thirteen orders of magnitude. Although the temperature dependence of DC and AC susceptibilities recalls a conventional spin-glass transition, nonlinear susceptibilities showing no divergences at the anomalous temperature, $T^{\ast }=16.87(7)$~K, deny that and instead hint at other mechanisms. Elastic neutron scattering together with previously measured muon results depict a slowly fluctuated ($\sim 10^{-5}$~sec) spin state above $T^{\ast }$. In juxtaposing the underlying simplest structure among frustrated magnets with an intricate hierarchy of time scales, FeGa${}_2$S${}_4$ can be a playground for studying temporal spin correlations in the two-dimensional limit.

10 pages, 5 figures

References in corpus (7)

• The quadrupolar phases of the S=1 bilinear-biquadratic Heisenberg model on the triangular lattice
• Ferromagnetic cluster spin-glass behavior in PrRhSn3
• Unusual superexchange pathways in a Ni triangular lattice of NiGa${}_2$S${}_4$ with negative charge-transfer energy
• Signature of a Z_2 vortex in the dynamical correlations of the triangular-lattice Heisenberg antiferromagnet
• Unconventional spin freezing and fluctuations in the frustrated antiferromagnet NiGa2S4
• Evidence for an exotic magnetic transition in the triangular spin system FeGa2S4
• Magnetic correlations in triangular antiferromagnet FeGa${}_2$S${}_4$