Critical behaviour in an insulating spin glass : field expansion and scaling

摘要: The amorphous manganese aluminosilicate with 15 at.% Mn is a spin glass freezing temperature T f =2.95 K. We have precisely measured slightly above its ac susceptibility in constant applied field H and low dc magnetization. cooled magnetization displays interesting relaxation phenomena close below . data can be fitted series expansion even powers of we determined the thermal variation first four terms series. non linear part described by universal scaling function two exponents: γ=3.1±0.1 β=1.4±0.1. By means numerical integration on this calculated equilibrium : agreement our precise SQUID measurements excellent for (T−T )/T 10 −2 Mesures de susceptibilite magnetique alternative en champ applique et l'aimantation statique d'un verre isolant, l'aluminosilicate amorphe au voisinage sa gel (T =2,95 K). Description des mesures l'aide developpement puissances paires determination la thermique 4 premiers termes ce developpement; description partie lineaire par une fonction universelle avec les exposants γ=3,1±0,1 β=1,4±0,1. Observation phenomenes dans refroidie sous