Direct observation of magnetic Friedel oscillation at Fe(001) surface

Abstract

Surface magnetism of Fe (001) was investigated by the in situ iron-57 probe layer method with a synchrotron Mössbauer source. The observed layer-by-layer internal hyperfine field shows a marked reduction at the surface and an oscillatory behavior with increasing depth in the individual layers below the surface. The calculated layer-by-layer hyperfine interactions (hyperfine field, isomer shift, and quadrupole shift) were consistent with the experimental results. The results give direct evidence for the magnetic Friedel oscillations, penetrating several layers from the Fe (001) surface.

Reflectivity spectra as absorption resonant spectra: is it correct?

“…Neumann et al, 1998); now it has a theoretical proof. Our results validate the application of the software developed for absorption spectrum fitting to the R-spectra undertaken in some Mo ¨ssbauer experimental work (Mitsui et al, 2012a(Mitsui et al, , 2016(Mitsui et al, , 2020Cini et al, 2018Cini et al, , 2020Cucinotta et al, 2020;Okabayashi et al, 2021a,b;Yokota et al, 2021;Ogawa et al, 2022). It follows that this approach is also applicable for XRMR experiments, i.e.…”

“…Therefore, this expression justifies the attempts to interpret the R-spectra in the total reflection region as the absorption resonant spectra and vindicates the use of the common software for Mo ¨ssbauer spectrum fitting (mentioned in Section 1), as done by e.g. Mitsui et al (2012aMitsui et al ( , 2016Mitsui et al ( , 2020, Cini et al (2018Cini et al ( , 2020, Cucinotta et al (2020), Okabayashi et al (2021a,b) and Yokota et al (2021). However, several effects can disturb the simplest linear connection between the reflectivity and absorption for angles in the total reflection region given by expression (5).…”

“…In many cases, e.g. for investigations of thin resonant layers or surfaces, the Mo ¨ssbauer or X-ray resonant spectra near the absorption edges are measured in reflection geometry at small grazing angles, or some larger glancing angles in the case of the soft X-ray region (Martens & Rabe, 1980;Greaves, 1990;Waki & Hirai, 1989;Andreeva et al, 1991Andreeva et al, , 2018Irkaev et al, 1993a;Isaenko et al, 1994;Kao et al, 1994;Filatova et al, 1995Filatova et al, , 2006Sacchi & Mirone, 1998;Neumann et al, 1998;Se `ve et al, 1999;Oppeneer et al, 2003;Bergmann et al, 2006;Goering et ISSN 1600-5767 al., 2010Smekhova et al, 2010;Domashevskaya et al, 2011;Mitsui et al, 2012aMitsui et al, , 2016Mitsui et al, , 2020Ro ¨hlsberger et al, 2012;Holldack et al, 2014;Haber et al, 2016Haber et al, , 2017Cini et al, 2018Cini et al, , 2020Majhi et al, 2018;Cucinotta et al, 2020;Engel et al, 2020;Okabayashi et al, 2021a;Yokota et al, 2021;Ogawa et al, 2022). These experiments were carried out at synchrotron stations, which supply investigators with angular collimated and energy-selective radiation.…”

“…Therefore, for analysis of the Mo ¨ssbauer spectra, many authors (see e.g. Mitsui et al, 2012aMitsui et al, , 2016Mitsui et al, , 2020Cini et al, 2018Cini et al, , 2020Cucinotta et al, 2020;Yokota et al, 2021;Okabayashi et al, 2021a,b;Ogawa et al, 2022) have interpreted the R-spectra measured at grazing angles in the total reflection region as a simple sum of the resonant absorption lines (absorption is proportional to the imaginary part of the refraction index n ¼ 1 þ =2 or susceptibility ) and applied the software developed for absorption spectrum fitting like MossA, UNIVEM-MS and MossWinn, CONFIT2000, and SpectrRelax. However, no mathematical support for this simplified R-spectrum treatment has been developed for the reflectivity calculation in the region of total external reflection.…”

Synchrotron Mössbauer source: trade-off between intensity and linewidth

“…Therefore, the small beam size makes the SMS extremely useful for studies at high pressure (Potapkin et al, 2013;Kupenko et al, 2019;Hamada et al, 2021), investigations of small iron-bearing inclusions in rocks (Andrault et al, 2018) and diamonds (Nestola et al, 2016), meteorites (Blukis et al, 2017), in surface studies (Cini et al, 2018;Fujiwara et al, 2021;Mitsui et al, 2020), and other scientific cases related to extremely small samples.…”