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Mitsui T, Sakai S, Li S, Ueno T, Watanuki T, Kobayashi Y, Masuda R, Seto M, Akai H. Magnetic Friedel Oscillation at the Fe(001) Surface: Direct Observation by Atomic-Layer-Resolved Synchrotron Radiation ^{57}Fe Mössbauer Spectroscopy. PHYSICAL REVIEW LETTERS 2020; 125:236806. [PMID: 33337194 DOI: 10.1103/physrevlett.125.236806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 07/13/2020] [Accepted: 10/16/2020] [Indexed: 06/12/2023]
Abstract
The surface magnetism of Fe(001) was studied in an atomic layer-by-layer fashion by using the in situ iron-57 probe layer method with a synchrotron Mössbauer source. The observed internal hyperfine field H_{int} exhibits a marked decrease at the surface and an oscillatory behavior with increasing depth in the individual upper four layers below the surface. The calculated layer-depth dependencies of the effective hyperfine field |H_{eff}|, isomer shift δ, and quadrupole shift 2ϵ agree well with the observed experimental parameters. These results provide the first experimental evidence for the magnetic Friedel oscillations, which penetrate several layers from the Fe(001) surface.
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Affiliation(s)
- T Mitsui
- National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo 679-5148, Japan
- National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma 370-1292, Japan
| | - S Sakai
- National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma 370-1292, Japan
| | - S Li
- National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma 370-1292, Japan
| | - T Ueno
- National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo 679-5148, Japan
- National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma 370-1292, Japan
| | - T Watanuki
- National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo 679-5148, Japan
- National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma 370-1292, Japan
| | - Y Kobayashi
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Asashironishi, Kumatori, Osaka 590-0494, Japan
| | - R Masuda
- Faculty of Science and Technology, Hirosaki University, Bunkyocho, Hirosaki, Aomori 036-8152, Japan
| | - M Seto
- National Institutes for Quantum and Radiological Science and Technology, Sayo, Hyogo 679-5148, Japan
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Asashironishi, Kumatori, Osaka 590-0494, Japan
| | - H Akai
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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Polarization Analysis in Mössbauer Reflectometry with Synchrotron Mössbauer Source. CONDENSED MATTER 2019. [DOI: 10.3390/condmat4010008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Polarization selection of the reflected radiation has been employed in Mössbauer reflectivity measurements with a synchrotron Mössbauer source (SMS). The polarization of resonantly scattered radiation differs from the polarization of an incident wave so the Mössbauer reflectivity contains a scattering component with 90° rotated polarization relative to the π-polarization of the SMS for some hyperfine transitions. We have shown that the selection of this rotated π→σ component from total reflectivity gives an unusual angular dependence of reflectivity characterized by a peak near the critical angle of the total external reflection. In the case of collinear antiferromagnetic interlayer ordering, the “magnetic” maxima on the reflectivity angular curve are formed practically only by radiation with this rotated polarization. The first experiment on Mössbauer reflectivity with a selection of the rotated polarization discovers the predicted peak near the critical angle. The measurement of the rotated π→σ polarization component in Mössbauer reflectivity spectra excludes the interference with non-resonant electronic scattering and simplifies the spectrum shape near the critical angle allowing for an improved data interpretation in the case of poorly resolved spectra. It is shown that the selected component of Mössbauer reflectivity with rotated polarization is characterized by enhanced surface sensitivity, determined by the “squared standing waves” depth dependence. Therefore, the new approach has interesting perspectives for investigations of surfaces, ultrathin layers and multilayers having complicated magnetic structures.
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