Multiple small angle neutron scattering in ferromagnets

TL;DR

This paper experimentally confirms the multiple small angle neutron scattering theory for ferromagnets, demonstrating a crossover from refraction to diffraction at a critical sample thickness, using pure Fe, Ni, and FeNi alloy.

Contribution

It provides experimental validation of recent theoretical predictions on neutron scattering in ferromagnets, including the critical thickness for scattering regime transition.

Findings

Confirmation of the multiple scattering theory in ferromagnets

Identification of a critical thickness L_0 for scattering regime change

Observation of the L^{1/2} to L dependence transition in neutron beam broadening

Abstract

The conclusions arising from the multiple small angle neutron scattering theory, developed recently by S.V. Maleyev, R.V. Pomortsev and Y.N. Skryabin [Phys. Rev. B 50 7133 (1994)] for the value of Born parameter more than 1, are experimentally confirmed by magnetic scattering from domain structure of pure Fe and Ni, as well as Fe_{65}Ni_{35} alloy. The crossover from multiple refraction to multiple Fraunhofer diffraction is found to be at a critical thickness L_0, where dependence of the neutron beam broadening w on sample thickness L changes from law L^{1/2} to law L.