Indium flux-growth of Eu2AuGe3: A new germanide with an AlB2 superstructure

The germanide Eu2AuGe3 was obtained as large single crystals in high yield from a reaction of the elements in liquid indium. At room temperature Eu2AuGe3 crystallizes with the Ca2AgSi3 type, space group Fmmm, an ordered variant of the AlB2 type: a = 857.7(4), b = 1485.5(10), c = 900.2(4) pm. The gold and germanium atoms build up slightly distorted graphite-like layers which consist of Ge6 and Au2Ge4 hexagons, leading to two different hexagonal-prismatic coordination environments for the europium atoms. Magnetic susceptibility data showed Curie−Weiss law behavior above 50 K and antiferromagnetic ordering at 11 K. The experimentally measured magnetic moment indicates divalent europium. The compound exhibits a distinct magnetic anisotropy based on single crystal measurements and at 5 K it shows a metamagnetic transition at ∼10 kOe. Electrical conductivity measurements show metallic behavior. The structural transition at 130 K observed in the single crystal data was very well supported by the conductivity mea...