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用中子相干非弹性散射测量了Fe_3Si在14K的自旋波色散关系。从自旋波二次方色散关系得到低温下自旋波劲度系数D_0=270meV·A~2。用Heisenberg模型可进一步导出Fe_3Si的有效交换积分J_(eff)。从磁化强度的温度依赖关系也获得了一个自旋波劲度系数D_m(O)。从两种不同方法获得的劲度系数的比较中发现在Fe_3Si中可能存在着Stoner激发,与早先工作相联系,本文还给出了从14K直到居里温度自旋波劲度系数D的温度依赖关系。 相似文献
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The effect of divalent cation substitution on the structure and magnetic properties of La1.2Sr1.8-xCaxMn2O7 (x = 0-0.900) is investigated in this paper. Partly replacing divalent cation Sr2+ by Ca2+ ions results in the weakening and then disappearance of long-range ferromagnetic ordering, and the formation of spin canting and low-temperature spin-glass. Based on structural analysis by Rietveld profile fitting, we suggest that this variation of magnetic property be related to a Jahn-Teller-type attice distortion of MnO6 octahedra due to the introduction of the smaller sized Ca2+ ions. 相似文献
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第一讲中子散射与散裂中子源 总被引:1,自引:0,他引:1
中子散射是研究物质微观结构和动态的理想工具之一,广泛地应用于凝聚态物质研究和应用的众多学科领域.散裂中子源能是新一代的加速器基脉冲中子源,能为中子散射提供高通量的脉冲中子.文章简明地介绍了中子散射的特点和它作为物质结构和动态探针的优越性,以及散裂中子源的基本原理、发展状况和多学科的应用优势.我国计划建设的散裂中子源CSNS中,靶站将由多片钨靶、铍/铁反射体和铁/重混凝土生物屏蔽体组成.质子束功率100kW下,脉冲中子通量约为2.4×1016n/cm2/s.第一期将设计建造高通量粉末衍射仪、高分辨粉末衍射仪、小角散射仪、多功能反射仪和直接几何非弹性散射仪等五台典型的中子散射谱仪,以覆盖大部分的中子散射研究领域. 相似文献
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A new family of the supramolecular antiferromagnetically exchange-coupled dimer of single-molecules magnets, [Mn4]2, really behave as a quantum mechanical coupled system and can be used for quantum computation [Tiron et al (2003) Phys. Rev. Lett. 91 227203]. We study the time evolution of [Mn4]2 dimer interacting 相似文献
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We report on alloys formed by replacing iron with manganese in the compound Dy2Fe17C1.0 Samples were characterized by X-ray diffraction and magnetic measure-ments, The 2:17-type structure can be crystallized in the whole range of manganese substitution. The Curie temperature of the series of Dy2Fe17-xMnxC1.0(x= 0-17) drops down considerably from 515K for x = 0 to about 20K for compounds with high manganese concentration, and the compensation point was observed in a narrow range of x≈4-6. The rapid decrease of the magnetization shows that the manganese substitution is not a simple magnetic dilution to the transition-metal sublattice mo-ment, it indicates that the moment of Mn may be antiparallel to that of Fe. The field dependence of the magnetization of Dy2Fe17-xMnxC1.0 may indicate the existence of the nonlinear magnetic structure for the samples with high Mn conoentrations. 相似文献
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用中子衍射方法研究了室温下KLiSO4的晶体结构,进一步确定了Li原子的位置,所得到的结果与近年采用X射线分析的结果在z/c上的差异小于1%。
关键词: 相似文献
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Resonant tunnelling of the magnetization in molecular crystal of [(Mn1-xCrx)12O12 (CH3COO)16(H2O)4]·2CH3COOH·4H2O(x=0,0.03,0.04,0.05) 下载免费PDF全文
The quantum tunnelling of magnetization (QTM) in single crystals of the single molecule magnet (Mn1-xCrx)12- Ac (x=0, 0.03, 0.04, 0.05) has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core. 相似文献
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本文报道用中子衍射测定的含硼稀土过渡族金属间化合物Pr_2(Fe_(0.8)Co_(0.2))_(14)B的晶体结构与磁结构。将中子三轴谱仪用作二轴粉末衍射仪,在室温测该化合物粉末样品的中子衍射强度,用轮廓精化法弥合衍射数据。该化合物属Nd_2Fe_(14)B类四方结构,α=8.8110A,c=12.2307A。设Pr,Fe和Co原子磁矩间为铁磁耦合,同一晶位的Fe,Co原子磁矩相等,存在沿c轴的易磁化方向,得到两个非等效Pr原子晶位Pr4f和Pr4g的磁矩1.2μ_B和1.4μ_B,和六个非等效铁族原子晶位T16k_1,T16k_2,T8j_1,T8j_2,T4e和T4c的磁矩2.2,2.1,1.9,3.1,1.6和1.0μ_B。Co原子在六种非等效晶位上的分布是平均的、等几率的。 相似文献
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