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The effect of laboratory magnetic fields on neutron reflection
Author(s) -
Felcher G. P.,
Adenwalla S.,
Goyette R. J.
Publication year - 1997
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889896013404
Subject(s) - neutron , perpendicular , magnetic field , reflection (computer programming) , neutron scattering , condensed matter physics , neutron diffraction , materials science , deuterium , amplitude , optics , phase (matter) , field (mathematics) , physics , nuclear magnetic resonance , atomic physics , nuclear physics , geometry , mathematics , quantum mechanics , pure mathematics , computer science , diffraction , programming language
Modest magnetic field gradients in the region of a reflecting sample surface (either magnetic or nonmagnetic) are sufficient to significantly perturb neutron reflectivity. Polarized neutron experiments on a 850 Å‐thick film of deuterated polystyrene on silicon showed a significant spin dependence of the reflectivity when the material was surrounded by magnetic circuitry that provided a transverse gradient ( ΔB ≃ 0.004 MA m −1 when integrated over the neutron path. The main effect of a field gradient is to modify the component of the neutron momentum perpendicular to the surface, k z 0 , to k z ± = ( k z 0 2 ± c ) 1/2 . The sign indicates the neutron spin orientation relative to the applied field and c is proportional to ΔB . The effect may be of some use: the insertion of a known gradient around a nonmagnetic sample permits the set of measurements necessary to obtain the reflectivity of the sample not only in amplitude but also in phase.