Structure and Spin-Glass Magnetism of the Mn(x)Ni(2)Zn(11–x) Pseudobinary γ-Brasses at Low Mn Contents

[Image: see text] The pseudobinary Mn(x)Ni(2)Zn(11–x) γ-brass-type phases at low Mn dopant levels (x = 0.1–0.5) were investigated. Crystal structures were determined for the two loading compositions of x = 0.3 and 0.5. The structures were solved in the cubic space group of I43m and are described in close analogy to the Ni(2)Zn(11) parent γ-brass that is based on the 26-atom cluster, consisting of inner tetrahedron (IT), outer tetrahedron (OT), octahedron (OH), and cuboctahedron (CO). The refined site occupancies of the Mn(x)Ni(2)Zn(11–x) (x = 0.3, 0.5) reveal that the cluster center, which is empty in the Ni(2)Zn(11), shows a partial occupation by Zn, with a partial depletion of Zn at the IT sites. The OH sites show a mixed Zn/Mn occupation. The OT and CO sites remain intact with respect to Ni(2)Zn(11). Magnetic properties were studied for the Mn(0.3)Ni(2)Zn(10.7) composition. The temperature-dependent zero-field-cooled and field-cooled magnetization, the ac susceptibility, the M(H) hysteresis curves, the thermoremanent magnetization, and the memory effect demonstrate typical broken-ergodicity phenomena of a magnetically frustrated spin system below the spin freezing temperature T(f) ≈ 16 K. The Mn(0.3)Ni(2)Zn(10.7) γ-brass phase classifies as a spin glass, originating predominantly from the random distribution of diluted Mn moments on the octahedral partial structure.