Magnetic Ground State Crossover in a Series of Glaserite Systems with Triangular Magnetic Lattices
Magnetic Ground State Crossover in a Series of Glaserite Systems with Triangular Magnetic Lattices
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一系列具有三角形磁晶格的玻璃晶系统中的磁基态交叉
DOI：
10.1021/acs.inorgchem.8b03418
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发表时间：
2019
影响因子：
4.6
通讯作者：
Kolis, Joseph W.
中科院分区：
文献类型：
--
作者：
Sanjeewa, Liurukara D.;Garlea, V. Ovidiu;McGuire, Michael A.;McMillen, Colin D.;Kolis, Joseph W.
报道了三种glaserite系列化合物Na2BaM(VO4)2, M = Mn, Mn0.6Co0.4和Co的磁性能。采用高温水热合成方法生长了大单晶。这种结构类型表现为一个三角形的磁性晶格，其中M2+ o6八面体与非磁性（VO4）3基团相互连接。所有结构均在室温下结晶，具有刚性三角对称（空间群pp3′m1）；然而，在较低的温度下，Na2BaMn(VO4)2和Na2BaMn0.6Co0.4(VO4)2都经历了低对称性（单斜，C2/c）的结构转变。体磁测量表明Mn-和co -结构分别为反铁磁性和铁磁性。Na2BaMn0.6Co0.4(VO4)2在0.5 K以下没有显示出任何长程有序，尽管在1.2 K附近的广泛热容量异常表明了短程磁有序或冻结成与化学无序和竞争性磁相互作用相关的自旋玻璃态。采用中子粉末衍射法测定了Na2BaMn(VO4)2和Na2BaCo(VO4)2的磁性结构。在零磁场下，Na2BaMn(VO4)2具有反铁磁结构，其矩沿八面体的c4轴排列，呈nsamel型排列。在0.3 K的外加磁场下，观察到磁性结构向完全极化状态的演化。Na2BaCo(VO4)2是一种Co矩平行于轴向的铁磁（FM）磁结构。讨论了这些结构与磁性能之间的关系。
The magnetic properties are reported for three members of the glaserite series of compounds, Na2BaM(VO4)2, M = Mn, Mn0.6Co0.4, and Co. Large single crystals are grown using a high-temperature hydrothermal synthesis method. This structure type exhibits a triangular magnetic lattice in which M2+O6octahedra are interconnected with nonmagnetic (VO4)3–groups. All the structures crystallize at room temperature with rigid trigonal symmetry (space groupP3̅m1); however, at lower temperatures both Na2BaMn(VO4)2and Na2BaMn0.6Co0.4(VO4)2undergo a structural transition to lower symmetry (monoclinic,C2/c). The bulk magnetic measurements indicate that Mn- and Co-structures are antiferromagnetic and ferromagnetic, respectively. Na2BaMn0.6Co0.4(VO4)2does not show any long-range ordering down to 0.5 K, although a broad heat capacity anomaly near 1.2 K suggests short-range magnetic order or freezing into a spin-glass-like state related to the chemical disorder and resulting competing magnetic interactions. The magnetic structures of Na2BaMn(VO4)2and Na2BaCo(VO4)2were determined using neutron powder diffraction. At zero magnetic field, Na2BaMn(VO4)2possesses an antiferromagnetic structure with the moments ordered in a Néel-type arrangement and aligned along the C4axis of the octahedra. Under applied magnetic field at 0.3 K, the evolution of the magnetic structure toward a fully polarized state is observed. Na2BaCo(VO4)2represents a ferromagnetic (FM) magnetic structure with Co moments aligned parallel to thec-axis direction. The relationships between these structures and magnetic properties are discussed.