DYNAMIC MAGNETIC-BEHAVIOR OF SOME DILUTED EUS AND EUSE COMPOUNDS

AC susceptibility measurements over a wide frequency range (1-108 Hz) on some EuxSr1-xS (x = 0.40 and 0.55) and EuxSr-xSe (x = 0.50 and 0.70) compounds are reported. The analysis of the experimental data is concerned on the complex 1/χ-plane which enables separate treatment of the influence of the demagnetizing effect on χ and on τc. A satisfactory description of the results by a so-called Cole-Cole relaxation process, χac ∞(1 + jωτc)1-h, is possible over the whole frequency range. This relaxation is detected below a temperature Th, well above the spin-glass freezing temperature Tf. The obtained relaxation time constant τc do not show any anomaly at or near T. The Cole-Cole description leads to an algebraic power-law-like behaviour in the time domain of the relaxation function. © 1990.