Flux Growth and Magnetoresistance Behavior of Rare Earth Zintl Phase EuMgSn

Reactions of europium and tin in
1:1 Mg/Al mixed flux produce large crystals of EuMgSn. This phase
crystallizes with the TiNiSi structure type in orthorhombic space
group Pnma (a = 8.0849(7) Å, b = 4.8517(4) Å, c = 8.7504(8) Å, Z = 4, R1 = 0.0137). The crystal
structure features europium cations positioned between puckered hexagonal
layers comprised of magnesium and tin atoms. Magnetic susceptibility
measurements indicate the europium in this phase is divalent, which
suggests that the compound is possibly valence-balanced as Eu2+Mg2+Sn4–. However, EuMgSn is
a metal as indicated by density of states calculations and electrical
resistivity behavior. This phase exhibits antiferromagnetic ordering
at TN = 10.9 K at low field (100 G) and
the ordering temperature decreases when a higher magnetic field is
applied. ac magnetization and field dependence of resistivity at 4.2
K reveal that there is a spin reorientation at 2 T, in agreement with
the metamagnetic transition shown in the dc magnetization versus field
data. Temperature dependence of resistivity at 2.5 T indicates that
EuMgSn has a large magnetoresistance up to −30% near its magnetic
ordering temperature.