Critical exponents of the ferromagnetic solid solution system EuxSr1-xS0.50Se0.50

Magnetisation and specific heat measurements are reported for ferromagnetic samples Eu x Sr 1-x S 0.50 Se 0.5O . Using modified Arrott plots the critical exponents beta , gamma , and delta are determined for different concentrations x down to the critical concentration x c . Whereas beta and gamma increase continuously with disorder up to beta =0.44 and gamma =1.84, delta remains at about delta =5.0. The Widom relation gamma = beta ( delta -1) is satisfied and universal functions describing the dependence of the scaled magnetisation on the scaled magnetic field exist for all concentrations. The authors show that the strong broadening of the specific heat anomaly close to xi c is consistent with a critical exponent of the specific heat alpha , as derived from the Rushbrooke relation (1972) 2= alpha +2 beta + gamma . The critical behaviour within the spin-glass regime x