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Abstract: A thermally activated magnetic relaxation is observed using neutron spin-echo in the pyrochlore slab (kagomé bilayer) compound in a restricted temperature range, , above a cross-over to a low temperature relaxation regime with a weaker temperature dependence. The activation energy of the thermally activated relaxation, of the order of 7meV, coincides with the energy of a phonon mode observed with neutron and Raman spectroscopy, indicating a phonon-assisted regime. The experimental observation of phonon-assisted process gives additional insight to the importance of spin–phonon coupling in frustrated magnets with regard to the models mostly based on purely magnetic interactions. [Copyright &y& Elsevier]

Non-collinear local configurations with null total moment are expected to be a hallmark of geometrically frustrated antiferromagnets. We attempt an experimental verification of such ideas in SrCr[sub 9x]Ga[sub 12-9x]O[sub 19] (SCGO), using the reverse Monte Carlo (RMC) analysis, recently adapted to the investigation of the magnetic correlations starting from total scattering powder data. The microscopic spin configurations obtained by RMC were used to calculate the spin nematic correlation function proposed to be of importance for classical spins on the kagomé lattice. In the low-temperature range our analysis shows a strong deviation from the behaviour of classical spins on the SCGO lattice obtained with our standard Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

We present local probe results on the honeycomb lattice antiferromagnet Ba3CuSb209. Muon spin relaxation measurements in a zero field down to 20 mK show unequivocally that there is a total absence of spin freezing in the ground state. Sb NMR measurements allow us to track the intrinsic susceptibility of the lattice, which shows a maximum at around 55 K and drops to zero in the low-temperature limit. The spin-lattice relaxation rate shows two characteristic energy scales, including a field-dependent crossover to exponential low-temperature behavior, implying gapped magnetic excitations. [ABSTRACT FROM AUTHOR]

We present an in-depth study of the magnetic properties of the spin-1 antiferromagnet 6HB-Ba3 NiSb2 O9. μSR measurements demonstrate that this material shows no static magnetism down to temperatures as low as 20 mK, making it a likely candidate for a quantum spin liquid state. Sb121 NMR shift measurements show that the local, intrinsic susceptibility levels off at temperatures below ~ 60 K. The NMR spin-lattice relaxation rate 1/T1 is essentially constant in temperature and the muon relaxation rate exhibits a low-temperature relaxation plateau, all indications of gapless spin excitations. Our local probe measurements are discussed in the context of several theories proposed for this material. [ABSTRACT FROM AUTHOR]