论文标题
带有Neel表面各向异性的球形纳米颗粒的磁性中子散射：分析处理
Magnetic neutron scattering from spherical nanoparticles with Neel surface anisotropy: Analytical treatment
论文作者
论文摘要
分析研究了单个球形纳米粒子的磁化谱和相关的磁性小角度散射横截面，并分析了尼尔表面各向异性。我们采用了一个包括各向同性交换相互作用，外部磁场，粒子核心中的单轴磁晶和单轴磁晶的各向异性以及表面的Neel各向异性的哈密顿量。使用扰动方法，可以将磁化曲线的测定降低到具有Neumann边界条件的Helmholtz方程，其解决方案以球形谐波和球形贝塞尔功能为代表。从所得的无限串联扩展中，我们通过分析计算傅立叶变换，该变换与磁性小角度中子散射横截面上的代数相关。使用Landau-Lifshitz方程将近似分析解决方案与数值解决方案进行了比较，该方程解释了问题的全部非线性。
The magnetization profile and the related magnetic small-angle neutron scattering cross section of a single spherical nanoparticle with Neel surface anisotropy is analytically investigated. We employ a Hamiltonian that comprises the isotropic exchange interaction, an external magnetic field, a uniaxial magnetocrystalline anisotropy in the core of the particle, and the Neel anisotropy at the surface. Using a perturbation approach, the determination of the magnetization profile can be reduced to a Helmholtz equation with Neumann boundary condition, whose solution is represented by an infinite series in terms of spherical harmonics and spherical Bessel functions. From the resulting infinite series expansion, we analytically calculate the Fourier transform, which is algebraically related to the magnetic small-angle neutron scattering cross section. The approximate analytical solution is compared to the numerical solution using the Landau-Lifshitz equation, which accounts for the full nonlinearity of the problem.
