(a) Schematic outline of the reflectometer showing the locations of the polarization equipment components. (b) Neutron spin polarization along the flight path of the instrument assuming zero spin-flip at the sample and in the spin-flippers. Only neutron spins antiparallel to the mirror magnetization transmit through the supermirror, turn into a longitudinal direction in the guide field and transverse again in the magnetic field around the sample. The post sample situation for the scattered beam is symmetric to the incident situation.
2D contour detector images and integrated intensity profiles plotted over the vertical direction of the detector (Y-Pixel) for (a) unpolarized beam, (b) beam transmitted through the polarizer only (c) unpolarized beam, spin separated by the analyzer supermirror. (d) Y-pixel integrated wavelength spectra of the direct beams shown in (a)–(c).
(a) Polarizer and (b) analyzer supermirror frames with RF spin-flipper components.
Intensity profile (a) and wavelength spectrum (b) of spin-dependent direct beam intensities. The wavelength integrated data (a) shows peak integration boundaries (vertical dotted line) and integrated background levels (horizontal dotted lines). NSF and SF peaks are indicated with shaded regions in yellow and aqua, respectively. Vertical lines in the wavelength spectrum (b) show the short and long λ cut-off.
Wavelength dependent polarization efficiencies of the neutron spin-flipper (a) and the combined polarizer-analyzer supermirror system expressed by ϕ = 1/2(1 − P 1 A 1) (b). The asymptotic function results from fitting of the polarizer and analyzer efficiencies shown in Fig. 6.
Wavelength dependent polarization efficiencies of the supermirrors obtained from reflectivity measurements of 20 Å Cr/3000 Å NiFe/Si. The efficiency has been fitted with asymptotic functions Eqs. (5) and (6) (red and black lines).
Decoupled polarization efficiencies of the polarizing elements in the PLATYPUS polarization setup. Both, the pre- and post-sample flipper show constant 99.7% flipping efficiency, while the polarizer and analyzer mirrors are fitted with Eqs. (5) and (6), respectively. A detuning of the flipping frequency of the pre-sample flipper leads reduces the efficiency of this flipper towards 97% in the short wavelength. Other efficiencies remain unaffected, showing the successful decoupling of the individual components in the calculations using Eqs. (2)–(4).
(a) Spin resolved reflectivity of a Cr(20 Å)/Ni0.8Fe0.2(300 Å)/Si magnetic thin film. The colored large symbols show the polarization efficiency corrected data, while uncorrected SF intensities are indicated by the smaller gray symbols. The effect of correction is less visible for NSF data and therefore not included in the plot. (b) Neutron spin resolved scattering length density profile obtained from fits to the corrected data shown in (a). Detailed values of the plots are shown in Table III.
(a) PNR of nominal Co(22 Å)/Cu0.94Mn0.06(154 Å) after field cooling in +30 mT at various temperatures and external fields (symbols). The lines are fits to the data resulting in a model structure of the sample shown in (b).
(a) Magnetic contrast reflectivity measurement of a β-mercaptoethanol layer assembled on a gold surface (data = symbols, lines = fits). (b) Spin-dependent neutron scattering length density profile derived from fits to the data. The β-mercaptoethanol can be resolved due to the additional measurement with a different contrast in the Ni0.8Fe0.2 layer.
(a) Magnetic contrast reflectivity measurement of a 1,2-dipalmitoyl-Sn-glycero-3-phosphothioethanol (DPPTE) layer assembled on a gold surface (data = symbols, lines = fits). (b) Spin-dependent neutron scattering length density profile derived from fits to the data.
Components and operational parameters of the PLATYPUS polarization system (n.a. = not applicable). Dimensions and instrument specific parameters of the components are described in Sec. II. Polarization efficiencies P of the components are described in Sec. III.
Neutron spin states for the different flipper settings on PLATYPUS.
Refined thickness, roughness, nuclear, and magnetic scattering length densities of the nominal Cr(20 Å)/Ni0.8Fe0.2(300 Å)/Si sample. Roughnesses are given in root mean square values.
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