Perpendicular magnetic anisotropy at Fe/Au(111) interface studied by M\"{o}ssbauer, x-ray absorption, and photoemission spectroscopies

The origin of the interfacial perpendicular magnetic anisotropy (PMA) induced in the ultrathin Fe layer on the Au(111) surface was examined using synchrotron-radiation-based M\"{o}ssbauer spectroscopy (MS), X-ray magnetic circular dichroism (XMCD), and angle-resolved photoemission spectroscopy (ARPES). To probe the detailed interfacial electronic structure of orbital hybridization between the Fe 3$d$ and Au 6$p$ bands, we detected the interfacial proximity effect, which modulates the valence-band electronic structure of Fe, resulting in PMA. MS and XMCD measurements were used to detect the interfacial magnetic structure and anisotropy in orbital magnetic moments, respectively. $In$-$situ$ ARPES also confirms the initial growth of Fe on large spin-orbit coupled surface Shockley states under Au(111) modulated electronic states in the vicinity of the Fermi level. This suggests that PMA in the Fe/Au(111) interface originates from the cooperation effects among the spin, orbital magnetic moments in Fe, and large spin-orbit coupling in Au. These findings pave the way to develop interfacial PMA using $p$-$d$ hybridization with a large spin-orbit interaction

Investigations on Local Magnetic Properties of Magnetic Thin Films Using Synchrotron-Radiation Mössbauer Spectroscopy

An energy domain grazing incidence iron-57 Mössbauer spectroscopy with synchrotron radiation has been developed to study the local magnetic properties of magnetic thin films. A high-brilliant iron-57 Mössbauer radiation, filtered from synchrotron radiation by a iron borate single crystal nuclear Bragg monochromator, allows us to perform the grazing incidence Mössbauer spectroscopy for the iron-57 sub-monolayer in a mirror-like film. This presentation introduces the principles, advantages and two typical applications of local magnetic structure analysis using a synchrotron Mössbauer source, which includes the study of Morin transition of an iridium doped Fe2O3(111) thin film by using the grazing incidence synchrotron Mössbauer spectroscopy and a direct observation of the Friedel oscillation at the Fe(001) surface by using the in-situ iron-57 probe layer method. Undoubtedly, the outstanding potential of the energy domain grazing incidence iron-57 Mössbauer spectroscopy facilitate the study of surface and interface magnetism in advanced magnetic and spintronic materials and devices.4th QST International Symposiu

Present state of synchrotron Mössbauer spectroscopy in BL11XU of SPring-8

Energy domain Mössbauer spectroscopy has been performing at the QST dedicated beamline (BL11XU) of SPring-8. In this presentation, I will introduce the present state of beamline operation, device performance including the nuclear Bragg monochromator, a brief introduction of applied research, future upgrade plans and research directions.Expert Workshop on Nuclear Resonant Scattering of Synchrotron Radiatio

Magmas Under Pressure: Advances in High-Pressure Experiments on Structure and Properties of Melts: Synchrotron Mössbauer Spectroscopy Measurement

This paper reviews recent progress of the high pressure 57Fe Mössbauer spectroscopy with a synchrotron Mössbauer source (SMS). The SMS can filter the Doppler-shifted 57Fe-Mössbauer radiation with a narrow bandwidth of nanoelectronvolt order from a broadband synchrotron radiation (SR). The focused SR beam makes it easy to measure a micron-sized sample in the diamond anvil cell (DAC), which enables the advanced Mössbauer experiments at extremely high-pressure-temperature conditions found in the Earth\u27s core. This review consists of the following contents: introduction and outline of the conventional Mössbauer spectroscopy, the high-pressure Mössbauer measurements with a DAC, advantages and disadvantages of the time-domain 57Fe Mössbauer spectroscopy with SR, the details on the SMS based Mössbauer spectroscopy, X-ray focusing optics for high-pressure SMS spectroscopy and its advantages in applications to Earth materials. Undoubtedly, the SMS based Mössbauer spectroscopy will open up new opportunities for geophysics and planetary science.備

The First Observation of Pure Nuclear Bragg Reflection from Natural Iron α-Fe2O3 by Synchrotron Mössbauer Diffraction

We have succeeded, for the fi rst time, in observing the pure nuclear Bragg re fl ection from the natural iron α -Fe2O3 by using a 57Fe synchrotron Mössbauer diffractometer at SPring-8 BL11XU. A well-resolved 111 reflection spectrum wasobtained. The spectrum is composed of two identical subspectra, except for the center shifts, originating from the two crystal grains slightly misaligned in angle. The deviation of the center shift and the attenuation of the inner lines imply that the dynamical effect of the diffraction still survives partially, while the symmetric and sharp line shapes indicate the escape from the effect. Our success strongly suggests that now a crystal-site-selective spectrum can be measured even with a natural iron specimen

Quantum Interference for Mössbauer Spectroscopy under Reflection Condition

スピントロニクス材料などの界面の磁性の振る舞いを調べる際に放射光メスバウアーを使った全反射スペクトル測定がなされている。すれすれ角付近では吸収のスペクトル形状を示すが臨界角付近を超えたあたりから電子散乱と核共鳴散乱の干渉した特異なスペクトル形状が現れる。実験ではいくつかの試料で特異な反射スペクトルを観測した。さらにこれを核共鳴散乱の異常散乱因子を考慮した反射スペクトルのシミュレーションを行うことでスペクトル形状をほぼ再現することに成功した。この特異なスペクトルを解析することで新たな位相因子計測法として利用可能であることを述べる。International Conference on the Applications of the Mössbauer Effect (ICAME 2021