RESUMO
The spin kinetics of adsorbed and liquid 3He in contact with a mixture of LaF3 (99.67 %) and DyF3 (0.33 %) 20 nm powders at temperatures of 1.5-4.2 K in magnetic fields up to 505mT was studied by pulsed nuclear magnetic resonance (NMR). Two-component of nuclear magnetic relaxation was observed in the experiment and theoretical relaxation model was proposed. The possible explanation of this phenomena can be carried out by a model that consider the exchange of magnetization of helium-3 nuclei located in the adsorbed layer and in the bulk of the liquid. The proposed relaxation model can be applied to other systems with the strong influence of adsorbed layer.
RESUMO
The magnetic properties of DyF3 powders with a particle size of 16 nm-7 µm were studied. The saturation magnetization decreases with decreasing particle size. It was shown that magnetic moments are ordered according to the density function of the Lorentz distribution, and the disorder parameter decreases with increasing particle size. A theoretical model is proposed to describe the magnetic properties, taking into account the influence of two mechanisms (clustering and surface layer effect) on the magnetization of DyF3 powder for the first time. The thickness of the surface layer for this case was determined as 0.5 ± 0.1 nm using the proposed model which is in agreement with the finite-size-scaling theory.
