title: 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 13 decades (10^{-13}-1 sec) using ultrahigh-resolution inelastic neutron scattering, muon spin relaxation, and ac and nonlinear susceptibility measurements. Unlike the short-ranged spatial correlations, the temperature dependence of the temporal correlations show distinct anomalies. The spin fluctuation rate decreases precipitously upon cooling towards T^{*}=8.5 K, but fluctuations on the microsecond time scale then persist in an anomalous dynamical regime for 4 K<T≤T^{*}. As this time scale exceeds that of single-site dynamics by 6 orders of magnitude, these fluctuations bear evidence of emergent degrees of freedom within the short-range correlated incommensurate state of NiGa_{2}S_{4}.
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan.|Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, Tokai, Ibaraki 319-1106, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nambu
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.|National Synchrotron Radiation Research Center, Neutron Group, Hsinchu 30077, Taiwan.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Gardner
authors.affiliation: Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
authors.forename: Douglas E
authors.initials: DE
authors.lastname: MacLaughlin
authors.affiliation: School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Stock
authors.affiliation: Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
authors.affiliation: Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Seth
authors.initials: S
authors.lastname: Jonas
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan.
authors.forename: Taku J
authors.initials: TJ
authors.lastname: Sato
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.|PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Nakatsuji
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.|Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Collin
authors.initials: C
authors.lastname: Broholm