Nature of the low energy excitations in the short range ordered region of Cs${}_2$CuCl${}_4$ as revealed by ${}^{133}$Cs NMR

Abstract

We report nuclear magnetic resonance measurements of the spin-1/2 anisotropic triangular lattice antiferromagnet Cs${}_2$CuCl${}_4$ as a function of temperature and applied magnetic field. The observed temperature and magnetic field dependence of the NMR relaxation rate suggests that low energy excitations in the short-range ordered region stabilized over a wide range of intermediate fields and temperatures of the phase diagram are gapless or nearly gapless fermionic excitations. An upper bound on the size of the gap of 0.037 meV $\approx J/10$ is established. The magnetization and NMR relaxation rate can be qualitatively described either by a quasi-1D picture of weakly coupled chains, or by mean-field theories of specific 2D spin liquids; however, quantitative differences exist between data and theory in both cases. This comparison indicates that 2D interactions are quantitatively important in describing the low-energy physics.

14 pages, 8 figures

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Cited by in corpus (11)

• Variational wave functions for the $S=1/2$ Heisenberg model on the anisotropic triangular lattice: Spin liquids and spiral orders
• Bold Diagrammatic Monte Carlo technique for frustrated spin systems
• Spin liquid phase in a spatially anisotropic frustrated antiferromagnet
• Spin correlations and Dzyaloshinskii-Moriya interaction in Cs${}_2$CuCl${}_4$
• Majorana spin liquid and dimensional reduction in Cs2CuCl4
• Dynamical reduction of the dimensionality of exchange interactions and the "spin-liquid" phase of $\kappa$-(BEDT-TTF)${}_{2}X$
• Hard-core boson approach to the spin-1/2 triangular-lattice antiferromagnet Cs${}_2$CuCl${}_4$ at finite temperatures in magnetic fields higher than the saturation field
• Spin relaxation in Cs${}_2$CuCl${}_{4-x}$Br${}_x$
• Singular spin-wave theory and scattering continua in the cone state of Cs_2CuCl_4
• Dynamic Simulations of Strongly Coupled Spin Ensembles for Inferring Nature of Electronic Correlations from Nuclear Magnetic Resonance
• Site-selective observation of spin dynamics of a Tomonaga-Luttinger liquid in frustrated Heisenberg chains