Structure and Spin-Glass Magnetism of the MnxNi2Zn11- x Pseudobinary γ-Brasses at Low Mn Contents

Sivaprasad Ghanta; Anustoop Das; Partha Pratim Jana; Stanislav Vrtnik; Darja Gačnik; Jože Luzar; Andreja Jelen; Primož Koželj; Magdalena Wencka; Janez Dolinšek

doi:10.1021/acs.inorgchem.1c01418

Structure and Spin-Glass Magnetism of the Mn_xNi₂Zn_{11- x} Pseudobinary γ-Brasses at Low Mn Contents

Inorg Chem. 2021 Aug 16;60(16):12226-12236. doi: 10.1021/acs.inorgchem.1c01418. Epub 2021 Aug 2.

Authors

Sivaprasad Ghanta¹, Anustoop Das¹, Partha Pratim Jana¹, Stanislav Vrtnik², Darja Gačnik², Jože Luzar², Andreja Jelen², Primož Koželj^{2

3}, Magdalena Wencka^{2

4}, Janez Dolinšek^{2

3}

Affiliations

¹ Department of Chemistry, Indian Institute of Technology, 721302 Kharagpur, India.
² J. Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
³ Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.
⁴ Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, PL-60-179 Poznań, Poland.

Abstract

The pseudobinary Mn_xNi₂Zn_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 Ni₂Zn₁₁ 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_xNi₂Zn_11-x (x = 0.3, 0.5) reveal that the cluster center, which is empty in the Ni₂Zn₁₁, 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 Ni₂Zn₁₁. Magnetic properties were studied for the Mn_0.3Ni₂Zn_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_0.3Ni₂Zn_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.