Pulsed-Field Ultrasonic Experiments in the Quasi-2D Antiferromagnet Cs2CuBr4

作者：Wolf B^*; Cong P T; Krueger N; Ritter F; Assmus W; Lang M

来源：Journal of Low Temperature Physics, 2013, 170(5-6): 236-241.

DOI：10.1007/s10909-012-0825-y

• Low-dimensional spin system
• Spin-phonon interaction
• Spin liquid

The magnetic insulators Cs2CuCl4 and Cs2CuBr4 are model systems for a frustrated quasi-two-dimensional triangular-lattice spin-1/2 Heisenberg antiferromagnet with a weak interlayer coupling. The quasi-two-dimensional character manifests itself in a broad maximum at T (max) in the magnetic susceptibility, which for Cs2CuCl4 has been found to mark the upper bound for a spin-liquid regime (R. Coldea et al. in Phys. Rev. B 68:134424, 2003). Motivated by the observation of characteristic B (2) dependencies in the elastic constants and ultrasound attenuation in the spin-liquid regime for this material, we look for corresponding signatures in the related Cs2CuBr4 compound at low temperatures Ta parts per thousand currency sign4.2 K and fields Ba parts per thousand currency sign50 T. We observe a softening of the elastic constant up to B (s similar to)32 T (Bayena) and a maximum in the sound attenuation at 0.86 B (s) . Both quantities exhibit the same characteristic B (2) dependence as found for Cs2CuCl4, suggesting the existence of a spin-liquid phase in Cs2CuBr4 as well.

• 出版日期2013-3