Spin Fluctuations from Hertz to Terahertz on a Triangular Lattice

Abstract

The temporal magnetic correlations of the triangular lattice antiferromagnet NiGa${}_2$S${}_4$ are examined through thirteen decades ($10^{-13}-1$~sec) using ultra-high-resolution inelastic neutron scattering, muon spin relaxation, AC and nonlinear susceptibility measurements. Unlike the short-ranged {\it spatial} correlations, the temperature dependence of the {\it temporal} correlations show distinct anomalies. The spin fluctuation rate decreases precipitously upon cooling towards $T^{\ast }=8.5$~K, but fluctuations on the microsecond time scale then persist in an anomalous dynamical regime for 4 K $<T\le T^{\ast }$. As this time scale exceeds that of single site dynamics by six orders of magnitude, these fluctuations bear evidence of emergent degrees of freedom within the short-range correlated incommensurate state of NiGa${}_2$S${}_4$.

References in corpus (9)

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• Quantum spin-liquid behavior in the spin-1/2 random Heisenberg antiferromagnet on the triangular lattice
• Unconventional Dynamics in Triangular Heisenberg Antiferromagnet NaCrO2
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• Spin dynamics and spin freezing behavior in the two-dimensional antiferromagnet NiGa${}_2$S${}_4$ revealed by Ga-NMR, NQR and $\mu$SR measurements
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• Two-dimensional ferromagnetic spin-orbital excitations in the honeycomb VI${}_3$
• Impact of the lattice on magnetic properties and possible spin nematicity in the S=1 triangular antiferromagnet NiGa${}_2$S${}_4$
• Spin current as a probe of the ${\mathbb{Z}}_2$-vortex topological transition in the classical Heisenberg antiferromagnet on the triangular lattice
• Orphan spins and bound in-gap states in the $S=\frac{5}{2}$ antiferromagnet CaFe${}_2$O${}_4$
• Slow spin tunneling in the paramagnetic phase of the pyrochlore Nd2Sn2O7
• Observation of topological $Z_2$ vortex fluctuations in the frustrated Heisenberg magnet NaCrO${}_2$
• US Muon Workshop 2021: A road map for a future Muon Facility
• Exfoliation and Optical Properties of S=1 Triangular Lattice Antiferromagnet NiGa${}_2$S${}_4$
• Unusual spin dynamics in the van der Waals antiferromagnet FeGa2S4
• Weak-coupling Mean-field Theory of Magnetic Properties of NiGa${}_2$S${}_4$
• Incommensurate Antiferromagnetic Order in the Fe-substituted Bi-2201 Cuprate in the Heavily Overdoped Regime