Crystal and magnetic properties of YbMn6−yFeySn6 (y ≤ 1)

We have synthesized the new YbMn6−yFeySn6 alloys (y = 0.25, 0.50, 0.75, and 1.00) and investigated their crystal and magnetic properties using X-ray diffraction and magnetization measurements. All alloys crystallize in the orthorhombic HoFe6Sn6 type of structure (Immm) with cell parameters shrinking upon increasing the iron content. In these alloys, the T = Mn/Fe sublattice orders ferromagnetically near TC ∼ 270 K. Yb does not magnetically order and its valency is estimated to be υ ∼ 2.6-2.7 from lattice constants. Guidelines are proposed to go through the Yb magnetic instability and the quantum phase transition associated with. The YbMn5.75Fe0.25Sn6 compound is a pure ferromagnet over the whole ordered temperature range, as the ternary YbMn6Sn6 parent compound, while the richer Fe alloys evolve upon cooling towards a low-magnetization state through a first-order transition. A field-induced metamagnetic transition allows recovering the ferromagnetic alignment and the alloys present maximal magnetizations of close magnitude (∼12.5 µB/f.u. at 5 K).