Magnetic supermirrors are widely used in polarized neutron applications. A key issue in producing these multilayer structures is to avoid residual stress in the layers, which may cause the layers to peel off. In this work He ion irradiation of 500 keV energy was applied at fluences of 1, 24, 50, 100×1014 ions/cm2 with the aim of reducing residual stress. Structural, magnetic and neutron-optical properties were investigated by grazing incidence high-angle X-ray diffraction, magneto-optical Kerr effect, conversion electron Mössbauer spectroscopy and polarized neutron reflectometry. We find a monotonous decrease of the tensile stress upon irradiation from 1.76 to 0.37 GPa with a coupled decrease of neutron reflectivity at the critical angle and decrease of the maximum polarizing efficiency from 23% to 4% at the highest fluence compared to the as-prepared reference supermirror. The supermirrors exhibit a superposition of uniaxial and fourfold in-plane magnetic anisotropy.
- Ion irradiation
- Neutron optics
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering