Magnons in spin-glasses in zero-field and in high magnetic fields: Experiments and theory

Abstract

Recent measurements of the specific heat and of the thermal conductivity of Eux Sr1−xS in high magnetic fields are reviewed. In the spin-glass and ferromagnetic concentration ranges the specific heat can be quantitavively accounted for in terms of magnon-like excitations, as shown by numerical calculations without any fit parameter. In particular, the exponential decrease of the magnetic specific heat with decreasing temperature in high fields, indicating a gap in the magnetic excitation spectrum, is reproduced. In the spin-glass range, heat transport is strongly facilitated by an external magnetic field, while below the percolation threshold xp = 0.13 no field effect on the thermal conductivity is seen.KeywordsHeat TransportPercolation ThresholdHigh Magnetic FieldMagnetic ExcitationLinear Temperature DependenceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.