| 1. |
- Andreeva, M. A., et al.
(author)
-
Polarization selection in Mössbauer reflectivity for magnetic multilayer investigation
- 2019
-
In: VII Euro-Asian Symposium on Trends In Magnetism. - : IOP Publishing.
-
Conference paper (peer-reviewed)abstract
- Mossbauer reflectivity experiment with polarization selection are reported. The use of the LiF polarization analyzer allows us to get the pi ->sigma' peak on the reflectivity curve at the critical angle and Mossbauer pi ->sigma' reflectivity spectra of reasonable quality at the critical angle and also at the Bragg angles of superlattice. The impressive difference of the reflectivity spectra measured near the critical angle with and without polarizations analysis is observed for [Fe-57(10)/V-10](20) multilayer characterizing by the ferromagnetic interlayer coupling. The combined fit of the whole set of spectra measured at different angles reveals the existence of antiferromagnetic Fe oxide phases in the top three bilayers. The experiment demonstrates benefits of the Mossbauer reflectivity with polarization analysis in ultrathin surface layer investigations.
|
|
| 2. |
- Baulin, R. A., et al.
(author)
-
Unique surface sensitivity to ferro- and antiferromagnetic phases by polarization analysis in synchrotron Mossbauer reflectivity
- 2021
-
In: SURFACES AND INTERFACES. - : Elsevier. - 2468-0230. ; 27
-
Journal article (peer-reviewed)abstract
- Polarization analysis of the reflected radiation has been performed in Mossbauer reflectivity measurements with a Synchrotron Mossbauer Source (SMS). Effective pi ->sigma' polarization selection is attained with LiF crystal ((6 2 2) 90 degrees-reflection for 14.4 keV radiation, angular acceptance similar to 100 '') capable of high pi ->pi' suppression. Basic features of the reflectivity with the rotated pi ->sigma' polarization are revealed in the experiment with the [Fe-57(10 ML)/V(20 ML)](20) multilayer. Selection of pi ->sigma' polarization component in Mossbauer reflectivity allows to exclude nonresonant electronic scattering, besides Mossbauer pi ->sigma' reflectivity spectra (R-spectra) contain only contributions from magnetized along the beam ferromagnetic phases. The antiferromagnetic iron oxides do not contribute to pi ->sigma' R-spectra (dichroic component is compensated). Therefore, in the Mossbauer reflectivity experiment supplemented by polarization analysis the data interpretation becomes more certain and gives information about depth position for ferromagnetic layers selectively. With this new technique we locate antiferromagnetic iron phases in the very top layer of [Fe-57(10 ML)/V(20 ML)](20) multilayer and ascertain the ferromagnetic ordered iron layers in the remaining part of the structure. This new approach in Mossbauer reflectivity has interesting perspectives for investigations of hyperfine interactions for iron complexes on the surface, ultrathin layers and multilayers with complicated magnetic structures.
|
|
| 3. |
|
|
| 4. |
- Andreeva, M. A., et al.
(author)
-
Nuclear resonant reflectivity with standing waves for the investigation of a thin 57Fe layer buried inside a superconducting Si/[Mo/Si]45/57Fe/Nb multilayer
- 2008
-
In: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 266:1, s. 187-196
-
Journal article (peer-reviewed)abstract
- A special multilayer sample Si/[Mo/Si]45/57Fe/Nb has been prepared for the depth selective investigations of the hyperfine fields in thin iron layer at low temperatures above and below the superconducting transition in the top Nb layer (Tc 8 K) by means of the nuclear resonant reflectivity with standing waves. The periodic multilayer [Mo/Si]45 below the iron layer in our sample was used as “a standing wave generator”. A weak magnetic hyperfine splitting in the 57Fe layer was detected just at low temperature. A slight variation of the nuclear resonant reflectivity time spectra measured above and below Tc was observed. At first it was supposed that this change of the spectrum shape is caused by the spatial modulation of ferromagnetic domains in the 57Fe layer caused by a proximity effect. A closer analysis, however, reveals that the spectrum variations are due to just the changes of the relative weights of the magnetic and paramagnetic phases in 57Fe layer.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Sergueev, I., et al.
(author)
-
Hyperfine Splitting and Room-Temperature Ferromagnetism of Ni at Multimegabar Pressure
- 2013
-
In: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 111:15
-
Journal article (peer-reviewed)abstract
- Magnetic and elastic properties of Ni metal have been studied up to 260 GPa by nuclear forward scattering of synchrotron radiation with the 67.4 keV Mossbauer transition of Ni-61. The observed magnetic hyperfine splitting confirms the ferromagnetic state of Ni up to 260 GPa, the highest pressure where magnetism in any material has been observed so far. Ab initio calculations reveal that the pressure evolution of the hyperfine field, which features a maximum in the range of 100 to 225 GPa, is a relativistic effect. The Debye energy obtained from the Lamb-Mossbauer factor increases from 33 me V at ambient pressure to 60 me V at 100 GPa. The change of this energy over volume compression is well described by a Gruneisen parameter of 2.09.
|
|
| 8. |
- Xu, Weiming M., et al.
(author)
-
Pressure-induced hydrogen bond symmetrization in iron oxyhydroxide
- 2013
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:17
-
Journal article (peer-reviewed)abstract
- Under high pressures the hydrogen bonds were predicted to transform from a highly asymmetric soft O-H center dot center dot center dot O to a symmetric rigid configuration in which the proton lies midway between the two oxygen atoms. Despite four decades of research on hydroxyl containing compounds, pressure induced hydrogen bond symmetrization remains elusive. Following single crystal x-ray diffraction, Mossbauer and Raman spectroscopy measurements supported by ab initio calculations, we report the H-bonds symmetrization in iron oxyhydroxide, FeOOH, resulting from the Fe3+ high-to-low spin crossover at above 45 GPa.
|
|
