Michels A, Viswanath R N, Barker J G, Birringer R, Weissmüller J
Institut für Nanotechnologie, Forschungszentrum Karlsruhe, Karlsruhe, Germany.
Phys Rev Lett. 2003 Dec 31;91(26 Pt 1):267204. doi: 10.1103/PhysRevLett.91.267204.
We have obtained the magnetic field dependence of static ferromagnetic correlations in nanocrystalline electrodeposited Co and Ni by means of the correlation function of the spin misalignment, determined from small-angle neutron scattering data. The approach yields a correlation length l(C), which is a measure for the spatial extent of inhomogeneities in the magnetization distribution. The correlation length depends strongly on the applied magnetic field with values ranging from 94 nm in nanocrystalline Co at low fields to about 15 nm at saturation. The results for l(C) indicate that in Co the main source of nonuniformity in the spin system is the anisotropy field of each individual crystallite, whereas in nanocrystalline Ni the main sources of spin disorder originate from twin faults or from the defect cores of grain boundaries.
我们通过自旋取向不一致的关联函数，根据小角中子散射数据，获得了纳米晶电沉积钴和镍中静态铁磁关联的磁场依赖性。该方法得出一个关联长度l(C)，它是磁化分布不均匀性空间范围的一种度量。关联长度强烈依赖于外加磁场，其值范围从低场下纳米晶钴中的94纳米到饱和时的约15纳米。l(C)的结果表明，在钴中自旋系统不均匀性的主要来源是每个微晶的各向异性场，而在纳米晶镍中自旋无序的主要来源则是孪晶界或晶界的缺陷核心。
