LAUSR

Abstract The magnetic properties of nanoparticles of Eu1−xFexCrO3 ( 0 ≤ x ≤ 1 ) prepared by a combustion reaction technique were investigated. An irreversible behavior in the magnetization was observed for a sample with x = 0.10 below the Neel temperature ( T N ) yielding a complex phase diagram. The irreversibility data was fitted to a de Almeida-Thouless line by using ϕ = 3.0 for the critical exponent and a glassy temperature T G of 174.4 K for H ≤ 40 kOe. The dynamics of the spins was investigated by measuring the ac magnetic susceptibility ( χ a c ) near T N for frequencies (f) in the range 10 − 10 4 Hz. The maximum in χ a c was found to shift to higher values of T for increasing values of f, yielding ≃ 0.003 for the shift per decade of f parameter. The Voguel-Fulcher law and a power-law were used for analyzing χ a c yielding τ 0 = 1.8 × 10 − 9 s ( = 1.6 × 10 − 15 s) for the characteristic relaxation time, E a / k B = 39.23 K for the activation energy and T G = 165.9 K ( = 167.5 K) for the Voguel-Fulcher (power-law) model. Moreover, the power-law yielded z ν = 5.62 for the product of the dynamical critical exponent (ν) with the one associated to the correlation length (z). The dependence of T N with the bonding angles Cr3+−O2−−Cr3+ was investigated for as-prepared samples yielding a trend contrary to the expected. The overall results were accounted for by taking into consideration the microstrain introduced by the sample preparation technique and by the ionic dopping.