small-angle neutron scattering (sans) ngb-30m sans  (National Institute of Standards and Technology)

Journal: IUCrJ

Article Title: Effect of annealing on the magnetic microstructure of high-pressure torsion iron: the relevance of higher-order contributions to the magnetic small-angle neutron scattering cross section

doi: 10.1107/S2052252523003937

Figure Lengend Snippet: Magnetic field dependence of the (over 2π) azimuthally averaged purely magnetic SANS cross section dΣ mag /dΩ of HPT Fe and nd Fe (log–log scales). The dΣ mag /dΩ curves have been obtained from the data plotted in Fig. 5 by subtracting the dΣ/dΩ at 8.0 T from the dΣ/dΩ at lower fields. Black solid lines: fits by equation (5 ) using the scattering and response functions defined by equations (6 )–(9 ), which are valid in the approach-to-saturation regime. Note that we have restricted our fit analysis to the HPT + 473 K and HPT + 673 K datasets, for which the magnetic correlation lengths can be spatially resolved within the available experimental q range [ i.e. for neutron data which do not exhibit a power-law behavior of dΣ mag /dΩ ∝ q − n with n varying from ∼3.5 (4.1) to ∼3.9 (3.4) for HPT Fe (nd Fe)].

Article Snippet: More recently, magnetic small-angle neutron scattering (SANS) experiments reported a significant increase of the effective magnetic anisotropy in HPT Fe (Oba et al. , 2020 ) and HPT Ni (Bersweiler et al. , 2021 ; Zaporozhets et al. , 2022 ), opening up a new route for the development of advanced magnetic materials using severe plastic-deformation techniques (Horita & Edalati, 2020 ).

Techniques:

Journal: IUCrJ

Article Title: Effect of annealing on the magnetic microstructure of high-pressure torsion iron: the relevance of higher-order contributions to the magnetic small-angle neutron scattering cross section

doi: 10.1107/S2052252523003937

Figure Lengend Snippet: Experimental 2D elastic total (nuclear + magnetic) unpolarized SANS cross section dΣ/dΩ of the HPT + 473 K Fe sample measured at the selected fields of ( a ) 8 T and ( b ) 0.2 T. ( c ) The corresponding purely magnetic SANS cross section dΣ mag /dΩ obtained by subtracting the dΣ/dΩ at the (near) saturation field of 8.0 T from the dΣ/dΩ at μ 0 H 0 = 0.2 T. The applied magnetic field H 0 is horizontal in the plane of the detector ( H 0 ⊥ k 0 ) and a logarithmic color scale is used in ( a )–( c ). ( d ) Experimental 1D purely magnetic SANS cross section obtained either by an azimuthal average over 2π, or from ±10° sector averages along (θ = 0°) or perpendicular (θ = 90°) to H 0 of the dΣ mag /dΩ plotted in ( c ) (log–log scale). ( e ) Azimuthal angle (θ) dependency of the magnetic scattering intensities obtained from ( c ). Note that in ( a )–( c ) dΣ/dΩ and dΣ mag /dΩ are plotted in polar coordinates with q (nm −1 ), θ (°) and intensity (cm −1 ). The data in ( a )–( c ) are shown up to q = 0.25 nm −1 . The white dashed lines in ( c ) are a visual guide to highlight the slight elongation of the scattering pattern along the field direction at smaller q .

Article Snippet: More recently, magnetic small-angle neutron scattering (SANS) experiments reported a significant increase of the effective magnetic anisotropy in HPT Fe (Oba et al. , 2020 ) and HPT Ni (Bersweiler et al. , 2021 ; Zaporozhets et al. , 2022 ), opening up a new route for the development of advanced magnetic materials using severe plastic-deformation techniques (Horita & Edalati, 2020 ).

Techniques: