Critical behavior study in GdNiAl2 intermetallic compound

Abstract

The critical behavior of the ternary intermetallic compound GdNiAl2 has been investigated around the second-order paramagnetic–ferromagnetic (PM–FM) phase transition TC based on the static magnetization data. Both the Modified Arrott plot and the Kouvel-Fisher method yield nearly the same critical exponents β = 0.368 ± 0.006 and γ = 1.042 ± 0.001, along with TC = 28.34 ± 0.01 K. Critical isotherm analysis at 30 K gives the result for the critical exponent δ = 3.59 ± 0.04. All three obtained critical exponents obey the Widom relation δ = 1 + γ/β and can also collapse the isothermal magnetization M-H-T data into two branches below and above TC in accordance with the single scaling equation M(H, ε) = εβf±(H/εβ+γ). This implies the self-consistence and accuracy of the exponents. The asymptotic critical exponents (βeff and γeff) are found to approach those of mean-field model, reflecting the existence of long-range magnetic interactions. The exchange interaction J(r) is found to decay as r−4.57 in the system. The long-range FM coupling in the system is suggested to be governed by the synergetic effect of hybridization and RKKY interactions.