Observation of magnetic coupling between distant metal centers in K3(MnO4)2 by muon spin relaxation measurements.

The site of a probe muon in the double salt K3(MnO4)2, which exhibits an antiferromagnetic phase at low temperature, and the Néel temperature of the salt were determined by zero-field muon spin relaxation. The picture shows the relaxation of the polarization asymmetry after muon insertion and a part of the crystal lattice.

Dispersive kinetics in discotic liquid crystals.

The dynamics of the discotic liquid-crystalline system, hexakis (n-hexyloxy) triphenylene (HAT6), is considered in the frame of the phenomenological model for rate processes proposed by Berlin. It describes the evolution of the system in the presence of the long-time scale correlations in the system, and we compare this with experimental quasielastic neutron scattering of the molecular assembly of HAT6 in the columnar phase. We interpret the parameters of this model in terms of nonextensive thermodynamics in which rare events in the local fast dynamics of some parts of the system control the slower dynamics of the larger molecular entity and lead to a fractional diffusion equation. The importance of these rare local events to the overall dynamics of the system is linked to the entropic index, this being obtained from the data within the model approach. Analysis of the waiting-time dependence from momentum transfer reveals a Lévy distribution of jump lengths, which allows us to construct the van Hove correlation function for discotic liquid-crystalline system.