Site-preferential design of itinerant ferromagnetic borides: experimental and theoretical investigation of MRh6B3 (M = Fe, Co).
Site-preferential design of itinerant ferromagnetic borides: experimental and theoretical investigation of MRh6B3 (M = Fe, Co).
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巡回铁磁硼化物的位点优先设计：MRh6B3（M = Fe、Co）的实验和理论研究。
DOI：
10.1021/ic2013655
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发表时间：
2011
影响因子：
4.6
通讯作者：
B. Fokwa
中科院分区：
文献类型：
--
作者：
P. R. N. Misse;M. Gilleßen;B. Fokwa
在水冷铜坩埚中，在氩气保护下，用电弧熔炼法合成了化合物MRh（6）B（3）（M = Fe，Co）的单相多晶样品和CoRh（6）B（3）的单晶。通过单晶和粉末X射线衍射以及EDX测量实现了新相的表征。这两个相是同型的，并且以六方Th（7）Fe（3）结构类型（空间群P6（3）mc，no.186，Z = 2）结晶。在这种结构中，磁活性原子（Fe，Co）优选地仅在三个可用的铑位点中的一个上发现，并且它们与铑一起构建互连的（Rh/M）（3）三角形的三维网络。磁性研究表明，在居里温度低于240 K（FeRh（6）B（3））和150 K（CoRh（6）B（3））时，两相都是铁磁有序的。第一性原理DFT计算正确地再现不仅晶格参数，但也在两个阶段的基态磁有序。这些计算还表明，在这两个阶段的长程磁有序发生通过间接的铁磁耦合的铁原子之间的铑介导。该磁结构模型还预测了FeRh（6）B（3）的饱和磁化强度为4.02 μ（B）（实验发现为3.60 μ（B）），CoRh（6）B（3）的饱和磁化强度为2.75 μ（B）。此外，这两个阶段被预测为金属导体预期这些金属间硼化物。
Single-phase polycrystalline samples of the compounds MRh(6)B(3) (M = Fe, Co) as well as single crystals of CoRh(6)B(3) have been synthesized by arc-melting the elements under a purified argon atmosphere in a water-cooled copper crucible. The characterization of the new phases was achieved by using single-crystal and powder X-ray diffraction as well as EDX measurements. The two phases are isotypic and crystallize in the hexagonal Th(7)Fe(3) structure type (space group P6(3)mc, no. 186, Z = 2). In this structure, the magnetically active atoms (Fe, Co) are preferentially found on only one of the three available rhodium sites, and together with rhodium they build a three-dimensional network of interconnected (Rh/M)(3) triangles. Magnetic properties investigations show that both phases order ferromagnetically below Curie temperatures of 240 K (for FeRh(6)B(3)) and 150 K (for CoRh(6)B(3)). First-principles DFT calculations correctly reproduce not only the lattice parameters but also the ground state magnetic ordering in the two phases. These calculations also show that the long-range magnetic ordering in both phases occurs via indirect ferromagnetic coupling between the iron atoms mediated by rhodium. This magnetic structural model also predicts the saturation magnetizations to be 4.02 μ(B) for FeRh(6)B(3) (3.60 μ(B) found experimentally) and 2.75 μ(B) for CoRh(6)B(3). Furthermore, both phases are predicted to be metallic conductors as expected for these intermetallic borides.