Potential magnetic structure in Eu 3 InAs 3 revealed by magnetization and thermodynamic study

We systematically investigate the magnetization and thermodynamic responses associated with the antiferromagnetic (AFM) transitions in magnetic semiconductor Eu InAs . The linear thermal expansion measurements reveal that axis expands whereas and axes contract with the onset of the two AFM transitions atTN1andTN2. Using a simplified mean-field model incorporating AFM exchange interactions, easy-axis anisotropy, and Zeeman coupling, we analyze the potential magnetic structure change associated with the spin-flop and spin-flip transitions in field. The agreement between experimental and calculated magnetization data suggests that the1/3plateau along axis results from a partial spin-flip transition in a multiple-easy-axis magnetic structure, where Eu -Eu and Eu sublattices order antiferromagnetically along the and axes atTN1andTN2, respectively. Consistently, field dependence of magnetic entropy determined using low- adiabatic magnetocaloric effect indicates that the number of the ordered Eu moments atTN1is nearly twice that atTN2. Our results demonstrate that the magnetic structure in materials with strong spin-lattice coupling can be simply approached by a combined magnetization and thermodynamic study.