Multiple magnetic scattering in small-angle neutron scattering of Nd–Fe–B nanocrystalline magnet

Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, U.; Ono, Kanta

doi:10.1038/srep28167

Cited by 10 publications

(7 citation statements)

References 45 publications

(70 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[14] for a review) provides information about the variations of both the magnitude and orientation of the magnetization vector field in the bulk and on a nanometer length scale (approximately 1-300 nm). SANS is extremely sensitive to longwavelength magnetization fluctuations, and it has only recently been employed for characterizing Nd-Fe-B-based permanent magnets: for example, the field dependence of characteristic magnetic length scales during the magnetization-reversal process in isotropic Nd-Fe-B-based nanocomposites [15] and in isotropic sintered Nd-Fe-B [16] was studied, the exchange-stiffness constant has been determined [17], the observation of the so-called spike anisotropy in the magnetic SANS cross section has been explained with the formation of flux-closure patterns [18], magnetic multiple scattering has been detected [19], textured Nd-Fe-B has been investigated [20], and the effect of grain-boundary diffusion on the magnetization-reversal process of isotropic [21] and hot-deformed textured [22][23][24] nanocrystalline Nd-Fe-B magnets has been studied. In this paper, exchange-coupled model magnets are investigated by SANS in order to quantitatively evaluate the spin disorder and to clarify the possible anisotropy of magnetic interactions.…”

Section: Introductionmentioning

confidence: 99%

Spin Structures of Textured and Isotropic Nd-Fe-B-Based Nanocomposites: Evidence for Correlated Crystallographic and Spin Textures

et al. 2017

View full text Add to dashboard Cite

We report the results of a comparative study of the magnetic microstructure of textured and isotropic Nd 2 Fe 14 B=α-Fe nanocomposites using magnetometry, transmission electron microscopy, synchrotron x-ray diffraction, and, in particular, magnetic small-angle neutron scattering (SANS). Analysis of the magnetic neutron data of the textured specimen and computation of the correlation function of the spinmisalignment SANS cross section suggests the existence of inhomogeneously magnetized regions on an intraparticle nanometer length scale, about 40-50 nm in the remanent state. Possible origins for this spin disorder are discussed: it may originate in thin-grain-boundary layers (where the material parameters are different than in the Nd 2 Fe 14 B grains), or it may reflect the presence of crystal defects (introduced via hot pressing), or the dispersion in the orientation distribution of the magnetocrystalline anisotropy axes of the Nd 2 Fe 14 B grains. X-ray powder diffraction data reveal a crystallographic texture in the direction perpendicular to the pressing direction-a finding which might be related to the presence of a texture in the magnetization distribution, as inferred from the magnetic SANS data.

show abstract

Section: Introductionmentioning

confidence: 99%

Spin Structures of Textured and Isotropic Nd-Fe-B-Based Nanocomposites: Evidence for Correlated Crystallographic and Spin Textures

et al. 2017

View full text Add to dashboard Cite

show abstract

“…SANS measurements produce 2D scattering profiles where the intensity is related to the squared sum of the nuclear and magnetic Fourier transforms [42]. In a fully-polarized SANS setup the neutron direction is established before and after interacting with the sample allowing for measurements of all four scattering cross-sections; spin up (↑) indicates a neutron that is aligned parallel to an external field while a spin down(↓) neutron is anti-parallel to the field.…”

Section: B Small Angle Neutron Scatteringmentioning

confidence: 99%

Spin Canting in Exchange Coupled Bi-Magnetic Nanoparticles: Interfacial Effects and Hard / Soft Layer Ordering

Kons,

Krycka,

Robles

et al. 2021

Preprint

View full text Add to dashboard Cite

We investigate the spatial distribution of spin orientation in magnetic nanoparticles consisting of hard and soft magnetic layers. The nanoparticles are synthesized in a core / shell spherical morphology where the magnetically hard, high anisotropy layer is CoFe 2 O 4 (CFO) while the lower anisotropy material is Fe 3 O 4 (FO). The nanoparticles have a mean diameter of ∼9.2 -9.6 nm and are synthesized as two variants: a conventional hard / soft core / shell structure with a CFO core / FO shell (CFO@FO) and the inverted structure FO core / CFO shell (FO@CFO). High resolution electron microscopy confirms the coherent spinel structure across the core / shell boundary in both variants while magnetometry indicates the nanoparticles are superparamagnetic at 300 K and develop a considerable anisotropy at reduced temperatures. Low temperature M vs. H loops suggest a multi-step reversal process. Temperature dependent small angle neutron scattering (SANS) with full polarization analysis reveals a strong perpendicular plane alignment of the spins near zero field, indicative of spin canting, but the perpendicular alignment quickly disappears upon application of a weak field and little spin ordering parallel to the field until the coercive field is reached. Above the coercive field of the sample, spins orient predominantly along the field direction. At both zero field and near saturation, the parallel magnetic SANS peak coincides with the structural peak, indicating the magnetization is uniform throughout the nanoparticle volume, while near the coercive field the parallel scattering peak shifts to higher momentum transfer (Q), suggesting that the coherent scattering volume is smaller and likely originates in the softer Fe 3 O 4 portion of the nanoparticle.

show abstract

“…PSD is typically positioned into an evacuated tank to avoid additional scattering occurring due to air (nitrogen). Schematic of SANS experimental setup is shown in Figure 1 [3].…”

Section: Small Angle Neutron Scattering (Sans)mentioning

confidence: 99%

SAXS and SANS Techniques for Surfactant Characterization: Application in Corrosion Science

Dwivedi¹,

Lepková²

2017

Application and Characterization of Surfactants

View full text Add to dashboard Cite

This chapter presents advances in the characterization of surfactants and detergents using small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) techniques. Surfactant molecules have been extensively used for corrosion prevention as part of commercial corrosion-inhibitor formulations. It is generally established that the interactions between surfactant molecule and metallic substrate play a key role in the formation of a corrosion-protective film. It is therefore essential to develop understanding about the nature of surfactant and detergent molecules in bulk solutions prior to formation of a surface film, as well as the mechanisms of their interactions with metallic substrates. These properties and interactions determine the properties of the surface film, including its persistency, and in turn define its protectiveness against corrosion. X-ray and neutron reflectivity methods are important investigating tools that could be used to characterize surfactant interactions with metallic substrates. These techniques have recently been utilized to investigate adsorption energies and contact angles between molecules or particles and variable substrates. This chapter addresses basic principles of these techniques and discusses their application for surfactant and detergent studies in corrosion science. Several case studies are presented and provide outlook for future prospects in this field of science.

show abstract

Multiple magnetic scattering in small-angle neutron scattering of Nd–Fe–B nanocrystalline magnet

Cited by 10 publications

References 45 publications

Spin Structures of Textured and Isotropic Nd-Fe-B-Based Nanocomposites: Evidence for Correlated Crystallographic and Spin Textures

Spin Structures of Textured and Isotropic Nd-Fe-B-Based Nanocomposites: Evidence for Correlated Crystallographic and Spin Textures

Spin Canting in Exchange Coupled Bi-Magnetic Nanoparticles: Interfacial Effects and Hard / Soft Layer Ordering

SAXS and SANS Techniques for Surfactant Characterization: Application in Corrosion Science

Contact Info

Product

Resources

About