Anisometric mesoscale nuclear and magnetic texture in sintered Nd-Fe-B magnets

0525030 - ÚJF 2021 RIV US eng J - Journal Article
Titov, I. - Honecker, D. - Mettus, D. - Feoktystov, A. - Kohlbrecher, J. - Strunz, Pavel - Michels, A.
Anisometric mesoscale nuclear and magnetic texture in sintered Nd-Fe-B magnets.
Physical Review Materials. Roč. 4, č. 5 (2020), č. článku 054419. ISSN 2475-9953. E-ISSN 2475-9953
Grant - others:AV ČR(CZ) StrategieAV21/23
Program: StrategieAV
Institutional support: RVO:61389005
Keywords : small-angle neutron scattering * SANS cross section * structure
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.989, year: 2020
Method of publishing: Limited access
https://doi.org/10.1103/PhysRevMaterials.4.054419

By means of temperature and wavelength-dependent small-angle neutron scattering (SANS) experiments on sintered isotropic and textured Nd-Fe-B magnets we provide evidence for the existence of an anisometric structure in the microstructure of the textured magnets. This conclusion is reached by observing a characteristic cross-shaped angular anisotropy in the total unpolarized SANS cross section at temperatures well above the Curie temperature. Comparison of the experimental SANS data to a microstructural model based on the superquadrics form factor allows us to estimate the shape and lower bounds for the size of the structure. Subtraction of the scattering cross section in the paramagnetic regime from data taken at room temperature provides the magnetic SANS cross section. Surprisingly, the anisotropy of the magnetic scattering is very similar to the nuclear SANS signal, suggesting that the nuclear structure is decorated by the magnetic moments via spin-orbit coupling. Based on the computation of the two-dimensional correlation function we estimate lower bounds for the longitudinal and transversal magnetic correlation lengths.
Permanent Link: http://hdl.handle.net/11104/0309264