Effect of Si interlayers on the magnetic and mechanical properties of Fe/Ge neutron polarizing multilayer mirrors

Journal Article · Thu Mar 15 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3694001· OSTI ID:22038887

Maruyama, R; Yamazaki, D; Hayashida, H; Soyama, K ^[1]; Okayasu, S ^[2]; Takeda, M ^[1]; Zettsu, N; Nagano, M; Yamamura, K ^[3]

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1. J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)
2. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)
3. Research Center for Ultra-precision Science and Technology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871 (Japan)

The neutron polarizing supermirror is one of the most important optical devices for polarizing neutron beams. To meet a variety of research demands, neutron polarizing supermirrors need to display high polarization efficiencies at low external magnetic fields. Fe/Si and Fe/Ge multilayers are typically used in neutron polarizing supermirrors because the contrast in scattering length densities almost vanishes for spin-down neutrons. The Fe/Si/Ge/Si multilayer, obtained by adding thin interlayers of Si to an Fe/Ge multilayer, is effective in reducing the external field strength necessary to achieve efficient neutron polarization. To gain insight into the mechanism that controls the required external field strength for a neutron polarizing supermirror, we investigated the magnetic and mechanical properties of Fe/Si, Fe/Ge, and Fe/Si/Ge/Si multilayers. The external field strength required to achieve efficient neutron polarization was found to be proportional to the compressive film stress. The compressive stress of the Fe/Si/Ge/Si multilayer was smaller by a factor of 4.4 and 2.7 than that of Fe/Si and Fe/Ge multilayers, respectively. These measurements and analyses showed that a reduction in the compressive film stress in the Fe/Si/Ge/Si multilayer permits the use of lower external field strength to achieve efficient neutron polarization. X-ray photoelectron spectroscopic studies showed that the formation of a Ge-Si solid solution in the Ge layer may explain the marked reduction in compressive stress in the case of the Fe/Si/Ge/Si multilayer. This study confirmed that a reduction in compressive film stress is very important for a high-performance neutron polarizing supermirror.

• OSTI ID: 22038887
• Journal Information: Journal of Applied Physics, Vol. 111, Issue 6; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
GAIN
GERMANIUM
INTERFACES
IRON
LAYERS
MAGNETIC FIELDS
MECHANICAL PROPERTIES
MIRRORS
NEUTRON BEAMS
POLARIZATION
RESIDUAL STRESSES
SCATTERING LENGTHS
SEMICONDUCTOR MATERIALS
SILICON
SOLID SOLUTIONS
SPIN
THIN FILMS
X-RAY PHOTOELECTRON SPECTROSCOPY