Competing magnetic order in EuPd$_3$Si$_2$

Single crystals of EuPd3Si2 were grown using a high-temperature EuPd-flux method. The material was structurally and chemically characterized by single-crystal x-ray diffraction, powder x-ray diffraction, Laue method and energy-dispersive x-ray spectroscopy. The structural analysis confirmed the orthorhombic crystal structure (space group Imma) but revealed differences in the lattice parameters and bond distances. The composition is close to the ideal 1:3:2 stoichiometry with an occupation of 7 % of the Si sites by Pd. The heat capacity, electrical resistivity, and magnetic susceptibility show two magnetic transitions indicating magnetic ordering below T$_{N1}$ = 61 K and
a spin reorientation at T$_{N2}$ = 40 K. The orthorhombic material shows magnetic anisotropy, with anisotropy constants K$_1$ = 7.1 × 10$^5$ J/m$^3$ and K$_2$ = 4.2 × 10$^5$ J/m$^3$, for field applied along the three main symmetry axes, which is summarized in the temperature-field phase diagrams. The susceptibility data hint to an alignment of the magnetic moments along [100] between T$_{N1}$ and T$_{N2}$. Below T$_{N2}$ the magnetic structure changes to an arrangement with moments canted away from [100]. ... mehrThe single crystals investigated in this study are suggested to show antiferromagnetic (AFM) order below T$_{N1}$ instead of ferromagnetism that sets in at higher T$_{C1}$ = 78 K which might originate from certain differences in the structure, composition or defects that have an impact on the dominant coupling constants of the RKKY interaction.