Reflective, polarizing, and magnetically soft amorphous Fe/Si multilayer neutron optics with isotope-enriched 11B4C inducing atomically flat interfaces

TL;DR

This paper introduces a novel Fe/Si multilayer with isotope-enriched 11B4C that achieves higher neutron reflectivity and polarization, with smoother interfaces and lower magnetic field requirements, improving neutron polarization optics.

Contribution

The study demonstrates that incorporating isotope-enriched 11B4C into Fe/Si multilayers results in amorphous, smooth interfaces and enhanced neutron optical performance, overcoming limitations of current multilayer polarizers.

Findings

Higher neutron reflectivity and polarization achieved

Elimination of magnetic coercivity and low-field saturation

Reduced diffuse scattering and improved interface quality

Abstract

The utilization of polarized neutrons is of great importance in scientific disciplines spanning materials science, physics, biology, and chemistry. Polarization analysis offers insights into otherwise unattainable sample information such as magnetic domains and structures, protein crystallography, composition, orientation, ion-diffusion mechanisms, and relative location of molecules in multicomponent biological systems. State-of-the-art multilayer polarizing neutron optics have limitations, particularly low specular reflectivity and polarization at higher scattering vectors/angles, and the requirement of high external magnetic fields to saturate the polarizer magnetization. Here, we show that by incorporating 11B4C into Fe/Si multilayers, amorphization and smooth interfaces can be achieved, yielding higher neutron reflectivity, less diffuse scattering and higher polarization. Magnetic coercivity is eliminated, and magnetic saturation can be reached at low external fields (>2 mT). This approach offers prospects for significant improvement in polarizing neutron optics, enabling; nonintrusive positioning of the polarizer, enhanced flux, increased data accuracy, and further polarizing/analyzing methods at neutron scattering facilities.