Critical behavior of ferromagnetic transition in La0.85Co1.68As2 crystal

The critical behavior of ferromagnetic transition is investigated by bulk magnetization measurements for La0.85Co1.68As2 crystal with a ThCr2Si2-type structure, grown by using NaAs as a flux, in which the vacancies on the both La and Co sites exist. The critical exponents [β = 0.388(3), γ = 1.44(2) and δ = 4.855(9)] with Curie temperature Tc = 99.4 K are obtained, whose self-consistency and reliability are verified by the Widom scaling law and the scaling equation. The critical exponents of ferromagnetic transition occurring in La0.85Co1.68As2 belong to the three-dimensional (3D) Heisenberg model, and suggest that the magnetic interaction decays as J(r)∼r−4.975 with a short range coupling. These results provide helpful information for understanding the mechanism of ferromagnetism emerging in La0.85Co1.68As2 compound.