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Kulchu A, Khalaniya RA, Mironov AV, Bogach AV, Aksenov SM, Lyssenko KA, Shevelkov AV. Interplay of two magnetic sublattices in related compounds Sm 2Mn 1-xGa 6-yGe y ( x = 0.1-0.3, y = 0.6-1.0) and Sm 4MnGa 12-yGe y ( y = 3.0-3.5) with different ordering of empty and filled (Ga,Ge) 6 octahedra. Dalton Trans 2024; 53:1506-1516. [PMID: 38131653 DOI: 10.1039/d3dt03505k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Single crystals of two new intermetallic phases Sm2Mn1-xGa6-yGey (x = 0.1-0.3, y = 0.6-1.0) and Sm4MnGa12-yGey (y = 3.0-3.5) were grown using a self-flux technique. According to single crystal X-ray diffraction data, Sm4MnGa12-yGey is characterised by the Y4PdGa12 structure type (a ∼ 8.65 Å; Im3̄m), while Sm2Mn1-xGa6-yGey formally adopts the K2PtCl6 structure type (a ∼ 8.71 Å; Fm3̄m). The general features of both compounds with rather similar crystal structures are represented by the alternation of empty and Mn-filled p-element octahedra, the order of which is determined by the Mn concentration. The diffraction data for Sm2Mn1-xGa6-yGey reveal a large concentration of Mn vacancies (x ∼ 0.3), which affects adjacent Ga/Ge atoms leading to their shift towards the vacancy. Both compounds demonstrate two ferromagnetic-like transitions and the presence of two interacting Mn and Sm magnetic sublattices. The Mn sublattice orders at TC1 of 143 K and 318 K, while the Sm one orders at lower temperatures at TC2 of 50 K and 280 K for Sm4MnGa8.6Ge3.4 and Sm2Mn0.74Ga5.1Ge0.9, respectively. The increase in Mn content not only increases the ordering temperatures, but also dramatically decreases the coercivity μ0HC from 230 mT to just 6.5 mT at 2 K. Despite the presence of two magnetically active sublattices in Sm2Mn0.74Ga5.1Ge0.9, the magnetic entropy change is quite low and only reaches 0.3 J kg-1 K-1 at T = 300 K and μ0H = 5 T, while the estimated relative cooling power (RCP) is about 36 J kg-1 at 5 T.
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Affiliation(s)
- Aleksandr Kulchu
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
- Faculty of Materials Science, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Roman A Khalaniya
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Andrei V Mironov
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Alexey V Bogach
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow 119991, Russia
| | - Sergey M Aksenov
- Laboratory of Arctic Mineralogy and Material Sciences, Kola Science Centre of RAS, Apatity 184209, Russia
- Geological Institute, Kola Science Centre of RAS, Apatity 184209, Russia
| | | | - Andrei V Shevelkov
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
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