Magnetic and Isothermal Magnetic Entropy Change Behavior of EuS

Magnetization measurements have been carried out to study the behavior of isothermal magnetic entropy change and critical magnetic equation of state of EuS. X-ray diffraction data exhibits rock salt-type cubic structure of EuS. Magnetization measurements indicate a ferromagnetic to paramagnetic phase transition at TC 16.8 K. Isothermal magnetic entropy change exhibits nonmonotonic behavior with temperature exhibiting a peak around TC. The peak value systematically increases with the increase of field change ΔH and the peak value, ΔSmax is 45 J/kg K for ΔH of 70 kOe. Arrott plots and superposition of normalized entropy change graphs for different ΔH with respect to rescaled temperature θ indicate the phase transition to be of second-order type. The temperature variation of exponent n of exponential variation of ΔS with ΔH shows nonmonotonic behavior displaying the minimum at TC for n 0.57. The magnetic critical exponents for the system are found to be β = 0.30, γ = 1.32, and δ = 5.32. Furthermore, analysis reveals that long-range exchange interaction is not supported in this system. Deviation of the critical exponents from the isotropic short-range Heisenberg exchange model in this system is surmised due to magnetic anisotropy and dipolar interactions.