Potential magnetic structure in Eu3InAs3 revealed by magnetization and thermodynamic study

We systematically investigate the magnetization and thermodynamic responses associated with antiferromagnetic (AFM) transitions in single crystals of the magnetic semiconductor Eu3InAs3. The linear thermal expansion measurements around the AFM transition temperatures, TN1 and TN2, indicate an expansion along the a axis and contraction along the b and c axes. The calculated ∆V/V(T) shows a continuous change at TN, indicating a second-order magnetic phase transition. Using a simplified mean-field model incorporating AFM exchange interactions, easy axis anisotropy, uniaxial single-ion anisotropy, and Zeeman coupling, we analyze the potential magnetic structure involving spin-flop (SFO) and spin-flip (SFI) transitions. The agreement between experimental and calculated M(H) data suggests that the 1/3 plateau in M∥b results from a partial SFI in a multiple-easy-axis magnetic structure, where Eu2-Eu3 and Eu1 sublattices order antiferromagnetically along the b and a directions at TN1 and TN2, respectively. The field dependence of magnetic entropy determined using a low-T adiabatic magnetocaloric effect (MCE) strongly supports that the quantity of the ordered Eu2+ moments at TN1 could be twice that at TN2. While neutron diffraction can precisely determine the magnetic structure, our magnetization and thermodynamic analysis provides a valuable approach for studying magnetic structures in materials with strong coupling between magnetic moments and lattice structure.