Crystal growth and magnetic structure of ternary silicide EuPd3Si2

The hexagonal $\mathrm{Ca}{\mathrm{Cu}}_{5}\text{\ensuremath{-}}\mathrm{type}$ structure $(P6/mmm)$ is the prototype for more than 100 ternary borides, gallides, and silicides, with general stoichiometry of $\mathrm{RT}{\mathrm{M}}_{3}{X}_{2} (R=\text{lanthanide/}\mathrm{alkaline}\phantom{\rule{0.28em}{0ex}}\mathrm{earth};\phantom{\rule{0.28em}{0ex}}\mathrm{TM}=\mathrm{transition}\phantom{\rule{0.28em}{0ex}}\mathrm{metal};\phantom{\rule{0.28em}{0ex}}X=\mathrm{B},\phantom{\rule{0.16em}{0ex}}\mathrm{Ga},\phantom{\rule{0.16em}{0ex}}\mathrm{Si},\phantom{\rule{0.16em}{0ex}}\mathrm{Ge})$. We report the synthesis, crystal structure, and bulk magnetic properties of polycrystalline and single crystal samples of $\mathrm{Eu}{\mathrm{Pd}}_{3}{\mathrm{Si}}_{2}$ and its nonmagnetic analog $\mathrm{Sr}{\mathrm{Pd}}_{3}{\mathrm{Si}}_{2}$. Both compounds crystallize in the orthorhombic space group symmetry $Imma$ (no. 74, $Z=2, oI12$) displaying pseudohexagonal symmetry. Ferromagnetic (FM) order of ${\mathrm{Eu}}^{2+}$ at ${T}_{\mathrm{C}1}=78\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and a spin-reorientation transition at ${T}_{\mathrm{C}2}=5\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ appear as distinctive features in bulk magnetization, specific heat, and resistivity/resistance measurements. Neutron powder diffraction measurements on $\mathrm{Eu}{\mathrm{Pd}}_{3}{\mathrm{Si}}_{2}$ confirm FM order of the ${\mathrm{Eu}}^{2+}$ spins below ${T}_{\mathrm{C}1}$, with the spins aligned along the $a$ axis below ${T}_{\mathrm{C}2}$. Electronic band structure calculations corroborate the crystal structure and the FM state for $\mathrm{Eu}{\mathrm{Pd}}_{3}{\mathrm{Si}}_{2}$, with a Pd $d\text{\ensuremath{-}}\mathrm{band}$ polarization in the same direction as the Eu $4f$ polarization, enhancing the observed spin moment.