The crossover from atomistic to continuous dynamic symmetry at the magnetic phase transition

It is suggested that the change from Curie–Weiss susceptibility to critical susceptibility has to be identified as crossover from atomistic to continuous dynamic symmetry. At this crossover the correlation length becomes of the order of the near neighbour distance. This enables dynamic percolation for lower temperatures and crossover to continuous symmetry. Continuous dynamic symmetry implies universality, i.e. a temperature dependence that is independent of the atomistic structures. This is in disagreement with the material specific magnon dispersion relations evaluated by inelastic neutron scattering. On the basis of these magnon dispersions the observed universality at the stable fixed point T = 0 cannot be explained. Instead a linear dispersion has to be postulated for all magnets. According to Goldstone, Salam and Weinberg (GSW) the quasi particles of this linear dispersion are non-interacting and massless. No interaction between the quasi particles requests that they have no magnetic moment and, as a consequence, must be spin compensated, in a similar way as is known from the Cooper pairs of superconductivity. Observation by neutron scattering therefore is impossible. The magnetic specific heat provides, so far, the only indirect access to the hypothesized spin-less magnetic quasi particles. We investigate experimental data of the ferromagnet EuS as a simple model material.