Critical behavior of spinel vanadate MnV1.95Al0.05O4

Abstract The critical properties of the spinel vanadate MnV1.95Al0.05O4 have been investigated by the Kouvel–Fisher method, and critical isotherm analysis. Reliable critical exponents β=0.492(3), γ=0.969(1) and δ=2.951(4) are obtained. Based on these critical exponents, the magnetization-field–temperature data around TC collapse into two independent curves obeying the single scaling equation M(H,e)=eβf±(H/eβ+γ). Moreover, the critical exponents are confirmed by the field dependence of the magnetic entropy change relation Δ S M | T = T C ∝ H n with n=1+(β+1)/(β+γ). The critical behavior of MnV1.95Al0.05O4 agrees with the prediction of the mean-field model with long range interaction. Compared with MnV2O4, the different critical behavior of MnV1.95Al0.05O4 might be because the doped Al ions destroy the collective frustration interaction between V ions. The ferromagnetism of MnV1.95Al0.05O4 is mainly related to the long range ferromagnetic interaction of Mn ions.