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arXiv 2602.21117cond-mat.mes-hall
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具有各向异性交换相互作用的铁磁纳米晶的磁小角中子散射

Magnetic small-angle neutron scattering by a nanocrystalline ferromagnet with anisotropic exchange interaction

Galkin Donetsk Institute for Physics and Engineering(加爾金頓涅茨克物理工程研究所)

Konstantin L. Metlov, Vladislav D. Zaporozhets

AI总结:

本文提出了一种微磁学框架,用于研究具有各向异性交换相互作用的纳米晶铁磁体的磁小角中子散射,并推导了具有六方对称性的交换张量在不同散射几何中的解析响应函数。

摘要:

本文提出了一种微磁学框架,用于磁小角中子散射(SANS),该框架考虑了中心对称纳米晶铁磁体中弱对称各向异性交换作用。交换相互作用通过一个通用四阶张量表达,分解为各向同性和偏极部分。我们从交换能和有效磁场出发,假设空间中磁化饱和度弱波动,求解微磁学问题以找到局部磁化矢量的空间分布,并计算平均(在纳米晶随机取向下的)SANS截面。各向同性部分重现了经典Heisenberg型SANS响应,而非零的偏极部分的交换张量导致磁SANS截面中出现新的角谐波。作为具体例子,推导了具有六方对称性的交换张量在垂直和平行散射几何中的解析响应函数。结果为识别和量化磁SANS实验中的对称交换各向异性提供了基础。

英文摘要:

A micromagnetic framework for magnetic small-angle neutron scattering (SANS) is presented that accounts for weak symmetric anisotropic exchange in centrosymmetric nanocrystalline ferromagnets. The exchange interaction is expressed via a general fourth-rank tensor decomposed into isotropic and deviatoric parts. We start with the exchange energy and effective field, assuming weakly fluctuating in space saturation magnetization, solve micromagnetic problem to find spatial distribution of local magnetization vector and compute the averaged (over random orientations of nanocrystals) SANS cross sections. The isotropic part reproduces the classical Heisenberg-type SANS response, while non-zero deviatoric part of the exchange tensor gives rise to new angular harmonics in the magnetic SANS cross section. As a specific example, analytical response functions for an exchange tensor with hexagonal symmetry in perpendicular and parallel scattering geometries are derived. The results provide a basis for identifying and quantifying symmetric exchange anisotropy in magnetic SANS experiments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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