Magnetic correlations in ferromagnets undergoing spin reorientation transitions
Magnetic correlations in ferromagnets undergoing spin reorientation transitions
复制标题
经历自旋重定向转变的铁磁体中的磁关联
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
A. D. Moral
中科院分区：
文献类型：
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作者：
A. D. Moral
纵向（平行于c轴）和横向（c轴）的自旋相关函数的计算与晶体轴对称的铁磁系统，并进行自旋重取向（SR）的影响下的竞争晶体电场（CEF）的轴向和平面字符的各向异性的过渡。结构因子是长程铁磁因子F（θ）delta（k）的组合，其振幅取决于SR角θ，加上有限波矢k处的有限贡献。这种小角中子散射（SANS）结构因子由磁振子散射产生的洛伦兹（L）项加上零点均匀量子自旋涨落产生的平方洛伦兹（L2）项贡献。在倾斜磁化相位中的SANS散射在磁畴壁内产生，并且因此具有畴壁宽度的数量级的相关长度。L和L2 SANS因子的前因子是自旋重取向角、CEF强度参数和自旋波刚度常数的复函数。这些结果进行了简要的讨论与最近的SANS实验中进行的tetraxNd（1-x）2Fe（14）B硬金属间化合物pseudotternary化合物。
The longitudinal (parallel to the c axis) and transverse (to the c axis) spin correlation functions are calculated for ferromagnetic systems with crystalline axial symmetries, and undergoing spin reorientation (SR) transitions under the effects of competing crystal electric field (CEF) anisotropies of axial and planar character. The structure factor is a combination of a long-range ferromagnetic one, F( theta ) delta (k), with amplitude dependent on the SR angle theta , plus a finite contribution at finite wavevectors k. This small-angle neutron scattering (SANS) structure factor is contributed by a Lorentzian (L) term, due to the magnon scattering, plus a squared Lorentzian (L2) term produced by zero-point uniform quantum spin fluctuations. This SANS scattering in the canted magnetization phase is produced within the magnetic domain walls, and therefore has a correlation length of the order of the domain wall width. The prefactors of the L and L2 SANS factors are complex functions of the spin reorientation angle and of the CEF strength parameters and spin-wave stiffness constant. These results are briefly discussed in connection with recent SANS experiments performed in the tetragonal (ErxNd1-x)2Fe14B hard intermetallic pseudoternary compounds.