Critical exponents and magnetocaloric response in Zintl phase EuIn2 X2 (X = As, P)

In the present studies, we have explored the nature of magnetic transition, critical magnetization scaling, and magnetocaloric effect of Zintl phase single crystalline EuIn2 X2 (X = P, As) compounds synthesized by flux-method. The magnetization susceptibilities of the two compounds revealed the ferromagnetically ordered Eu2+ moment below 24 K in EuIn2P2 while in EuIn2As2 Eu2+ moment couple antiferromagnetically below 16.3 K. A comprehensive study of the magnetization data is performed in the critical regime utilizing modified Arrott plots (MAP), the Kouvel-Fisher (KF) method, universal curve scaling, and the magnetocaloric effect. For EuIn2P2, the magnetization isotherms follow MAP with critical exponents β = 0.257, γ = 0.86, and δ = 4.45 for the magnetic field applied along the c-axis (H||c) and β = 0.226, γ = 1.10, and δ = 5.87 for the magnetic field applied along the ab-plane (H||ab). For EuIn2As2, the values are β = 0.245, γ = 0.81, and δ = 4.31 and β = 0.244, γ = 0.89, and δ = 4.65 for H||c and H||ab plane, respectively. The Kouvel-Fisher and universal scaling plots of the magnetization isotherms further corroborated the reliability of our analysis and the exponents’ values. A reasonable magnetocaloric effect -ΔSm = 9.55 Jkg−1K−1 and 10.80 Jkg−1K−1 for 5T magnetic field change is observed for H||c and H||ab plane for EuIn2P2, respectively. The values of -ΔSm for EuIn2As2 are 10.40 Jkg−1K−1 and 12.75 Jkg−1K−1 for H||c and H||ab plane. The critical exponents derived from the magnetocaloric effect (MCE) are n = 0.49(5), 0.45(3) and δ = 5.17(4), 5.74(1) for EuIn2P2 and n = 0.33(1), 0.34(2) and δ = 5.08(5), 6.54(6), respectively for H||c and H||ab plane for EuIn2P2 and EuIn2As2. The exponents derived from the MCE are marginally elevated, but they remain in substantial concordance with the values inferred from the magnetic isotherm study.