Electron magnetic circular dichroism opens a new door to explore magnetic properties by transmitted electrons in the transmission electron microscope. However, obtaining quantitative magnetic parameters, such as spin ...Electron magnetic circular dichroism opens a new door to explore magnetic properties by transmitted electrons in the transmission electron microscope. However, obtaining quantitative magnetic parameters, such as spin and orbital magnetic moment with element-specificity, goes a long way along with the development and improvement of this technique both in theoretical and experimental aspects. In this review, we will give a detailed description of the quantitative electron magnetic circular dichroism（EMCD） technique to measure magnetic parameters with spin-specificity, element-specificity,site-specificity, and orbital-spin-specificity. The discussion completely contains the procedures from raw experimental data acquisition to final magnetic parameters, together with the related custom code we have developed.展开更多
IN recent years,magnetic circular dichroism(MCD)demonstrated its unique advantages inanalysis of metal porphyrin and its interaction with protein.However,there were few re-ports about the application of MCD method in ...IN recent years,magnetic circular dichroism(MCD)demonstrated its unique advantages inanalysis of metal porphyrin and its interaction with protein.However,there were few re-ports about the application of MCD method in photosynthesis field.It is known that most pig-ments in PS Ⅱ-RC are metal porphyrin type.This note reports the MCD spectrum of PS Ⅱ-展开更多
X-ray magnetic circular dichroism in absorp- tion of the single-crystal iron layer deposited epitaxially on MgO substrate is studied. Spin and orbital moment, 0.069 and 2.33 μB, respectively, are calculated in terms ...X-ray magnetic circular dichroism in absorp- tion of the single-crystal iron layer deposited epitaxially on MgO substrate is studied. Spin and orbital moment, 0.069 and 2.33 μB, respectively, are calculated in terms of the XMCD sum rules. Our results are accordant to those pub- lished. Experiments show that the orbital moment would be decreased to that in bulk materials as iron film is thinned down, but spin moment changes little.展开更多
X-ray magnetic circular dichroism （XMCD） has become an important and powerful tool because it allows the study of material properties in combination with elemental specificity, chemical state specificity, and magnet...X-ray magnetic circular dichroism （XMCD） has become an important and powerful tool because it allows the study of material properties in combination with elemental specificity, chemical state specificity, and magnetic specificity. A new soft X-ray magnetic circular dichroism apparatus has been developed at the Beijing Synchrotron Radiation Facility （BSRF）. The apparatus combines three experimental conditions： an ultra-high-vacuum environ- ment, moderate magnetic fields and in-situ sample preparation to measure the absorption signal. We designed a C-type dipole electromagnet that provides magnetic fields up to 0.5 T in parallel （or anti-parallel） direction rela- tive to the incoming X-ray beam. The performances of the electromagnet are measured and the results show good agreement with the simulation ones. Following film grown in situ by evaporation methods, XMCD measurements are performed. Combined polarization corrections, the magnetic moments of the Fe and Co films determined by sum rules are consistent with other theoretical predictions and experimental measurements.展开更多
In this work, the magnetocrystalline anisotropy energy(MAE) on the surface of FeCoalloy film is extracted from x-ray magnetic linear dichroism(XMLD) experiments. The result indicates that the surface MAE value is nega...In this work, the magnetocrystalline anisotropy energy(MAE) on the surface of FeCoalloy film is extracted from x-ray magnetic linear dichroism(XMLD) experiments. The result indicates that the surface MAE value is negatively correlated with thickness. Through spectrum calculations and analysis, we find that besides the thickness effect, another principal possible cause may be the shape anisotropy resulting from the presence of interface roughness. These two factors lead to different electron structures on the fermi surface with different exchange fields, which produces different spin–orbit interaction anisotropies.展开更多
Three ultra-short-period W/B4C multilayers （1.244 nm, 1.235 nm and 1.034 nm） have been fabricated and used for polarization measurement at the 4BTB Beamline at the Beijing Synchrotron Radiation Facility （BSRF）. By...Three ultra-short-period W/B4C multilayers （1.244 nm, 1.235 nm and 1.034 nm） have been fabricated and used for polarization measurement at the 4BTB Beamline at the Beijing Synchrotron Radiation Facility （BSRF）. By using the rotating analyzer ellipsometry method, the linear polarization degree of light emerging from this beamline has been measured and the circular polarization evaluated for 700-860 eV. The first soft X-ray magnetic circular dichroism measurements are carried out at BSRF by positioning the beamline aperture out of the plane of the electron storage ring.展开更多
The growth of Fe nanoclusters oN the Ge（001） surface has been studied using low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM results indicate that Fe nucl...The growth of Fe nanoclusters oN the Ge（001） surface has been studied using low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM results indicate that Fe nucleates on the Ge（001） surface, forming well-ordered nanoclusters of uniform size. Depending on the preparation conditions, two types of nanoclusters were observed having either four or sixteen Fe atoms within a nanocluster. The results were confirmed by DFT calculations. Annealing the nanoclusters at 420 K leads to the formation of nanorow structures, due to cluster mobility at such temperature. The Fe nanoclusters and nanorow structures formed on the Ge（001） surface show a superparamagnetic behaviour as measured by X-ray magnetic circular dichroism.展开更多
Spin chiral anisotropy(SChA)refers to the occurrence of different spin polarization in antipodal chiral structures.Herein,we report the SChA in diamagnetic chiral mesostructured In2O3 films(CMIFs)with manifestation of...Spin chiral anisotropy(SChA)refers to the occurrence of different spin polarization in antipodal chiral structures.Herein,we report the SChA in diamagnetic chiral mesostructured In2O3 films(CMIFs)with manifestation of chirality-dependent magnetic circular dichroism(MCD)signals.CMIFs were grown on fluorine-doped tin dioxide conductive glass(FTO)substrates,which were synthesized via a hydrothermal route,with malic acid used as the symmetry-breaking agent.Two levels of chirality have been identified in CMIFs:primary nanoflakes with atomically twisted crystal lattices and secondary helical stacking of the nanoflakes.CMIFs exhibit chirality-dependent asymmetric MCD signals due to the different interactions of chirality-induced effective magnetic field and external magnetic field,which distinguish from the commonly observed external magnetic fielddependent symmetric MCD signals.These findings provide insights into spin manipulation of spin-paired diamagnets.展开更多
Chirality is omnipresent among biological materials,such as amino acids,sugars,and DNA[1].It plays a vital role in wide-ranging applications including biomedicine,nonlinear optics,and negative index metamaterials[2-4]...Chirality is omnipresent among biological materials,such as amino acids,sugars,and DNA[1].It plays a vital role in wide-ranging applications including biomedicine,nonlinear optics,and negative index metamaterials[2-4].The chiral structures of molecules and supramolecular systems may cause differential absorption of left-and right-handed circularly polarized light leading to circular dichroism(CD)activity.展开更多
文摘Electron magnetic circular dichroism opens a new door to explore magnetic properties by transmitted electrons in the transmission electron microscope. However, obtaining quantitative magnetic parameters, such as spin and orbital magnetic moment with element-specificity, goes a long way along with the development and improvement of this technique both in theoretical and experimental aspects. In this review, we will give a detailed description of the quantitative electron magnetic circular dichroism（EMCD） technique to measure magnetic parameters with spin-specificity, element-specificity,site-specificity, and orbital-spin-specificity. The discussion completely contains the procedures from raw experimental data acquisition to final magnetic parameters, together with the related custom code we have developed.
文摘IN recent years,magnetic circular dichroism(MCD)demonstrated its unique advantages inanalysis of metal porphyrin and its interaction with protein.However,there were few re-ports about the application of MCD method in photosynthesis field.It is known that most pig-ments in PS Ⅱ-RC are metal porphyrin type.This note reports the MCD spectrum of PS Ⅱ-
文摘X-ray magnetic circular dichroism in absorp- tion of the single-crystal iron layer deposited epitaxially on MgO substrate is studied. Spin and orbital moment, 0.069 and 2.33 μB, respectively, are calculated in terms of the XMCD sum rules. Our results are accordant to those pub- lished. Experiments show that the orbital moment would be decreased to that in bulk materials as iron film is thinned down, but spin moment changes little.
基金Supported by National Natural Science Foundation of China(61204008)
文摘X-ray magnetic circular dichroism （XMCD） has become an important and powerful tool because it allows the study of material properties in combination with elemental specificity, chemical state specificity, and magnetic specificity. A new soft X-ray magnetic circular dichroism apparatus has been developed at the Beijing Synchrotron Radiation Facility （BSRF）. The apparatus combines three experimental conditions： an ultra-high-vacuum environ- ment, moderate magnetic fields and in-situ sample preparation to measure the absorption signal. We designed a C-type dipole electromagnet that provides magnetic fields up to 0.5 T in parallel （or anti-parallel） direction rela- tive to the incoming X-ray beam. The performances of the electromagnet are measured and the results show good agreement with the simulation ones. Following film grown in situ by evaporation methods, XMCD measurements are performed. Combined polarization corrections, the magnetic moments of the Fe and Co films determined by sum rules are consistent with other theoretical predictions and experimental measurements.
基金supported by the National Natural Science Foundation of China(Grant Nos.11075176 and 11375131)
文摘In this work, the magnetocrystalline anisotropy energy(MAE) on the surface of FeCoalloy film is extracted from x-ray magnetic linear dichroism(XMLD) experiments. The result indicates that the surface MAE value is negatively correlated with thickness. Through spectrum calculations and analysis, we find that besides the thickness effect, another principal possible cause may be the shape anisotropy resulting from the presence of interface roughness. These two factors lead to different electron structures on the fermi surface with different exchange fields, which produces different spin–orbit interaction anisotropies.
基金Supported by National Natural Science Foundation of China(11075176, 10435050)
文摘Three ultra-short-period W/B4C multilayers （1.244 nm, 1.235 nm and 1.034 nm） have been fabricated and used for polarization measurement at the 4BTB Beamline at the Beijing Synchrotron Radiation Facility （BSRF）. By using the rotating analyzer ellipsometry method, the linear polarization degree of light emerging from this beamline has been measured and the circular polarization evaluated for 700-860 eV. The first soft X-ray magnetic circular dichroism measurements are carried out at BSRF by positioning the beamline aperture out of the plane of the electron storage ring.
基金This work was supported by Science Foundation Ireland （Principal Investigator grant No. 06/IN.1/191 and Research Frontiers Programme grant No. 07/ RFP/MASF185）. The authors wish to thank Trinity College High Performance Cluster, funded by the Higher Education Authority under the Program for Research in Third Level Institutes, for the use of their computing facilities.
文摘The growth of Fe nanoclusters oN the Ge（001） surface has been studied using low-temperature scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. STM results indicate that Fe nucleates on the Ge（001） surface, forming well-ordered nanoclusters of uniform size. Depending on the preparation conditions, two types of nanoclusters were observed having either four or sixteen Fe atoms within a nanocluster. The results were confirmed by DFT calculations. Annealing the nanoclusters at 420 K leads to the formation of nanorow structures, due to cluster mobility at such temperature. The Fe nanoclusters and nanorow structures formed on the Ge（001） surface show a superparamagnetic behaviour as measured by X-ray magnetic circular dichroism.
基金supported by the National Key Research and Development Program of China(No.2021YFA1200301,S.A.C.)the National Natural Science Foundation of China(Nos.21931008,S.A.C.and 21975184,Y.Y.D.)Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University(No.21TQ1400219).
文摘Spin chiral anisotropy(SChA)refers to the occurrence of different spin polarization in antipodal chiral structures.Herein,we report the SChA in diamagnetic chiral mesostructured In2O3 films(CMIFs)with manifestation of chirality-dependent magnetic circular dichroism(MCD)signals.CMIFs were grown on fluorine-doped tin dioxide conductive glass(FTO)substrates,which were synthesized via a hydrothermal route,with malic acid used as the symmetry-breaking agent.Two levels of chirality have been identified in CMIFs:primary nanoflakes with atomically twisted crystal lattices and secondary helical stacking of the nanoflakes.CMIFs exhibit chirality-dependent asymmetric MCD signals due to the different interactions of chirality-induced effective magnetic field and external magnetic field,which distinguish from the commonly observed external magnetic fielddependent symmetric MCD signals.These findings provide insights into spin manipulation of spin-paired diamagnets.
基金This work was supported by the National Natural Science Foundation of China(Nos.21975095,21671079 and 21373100)the“111”Project of China(No.B17020)the Fund of the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(Jilin University),China(No.1G3211454461).
文摘Chirality is omnipresent among biological materials,such as amino acids,sugars,and DNA[1].It plays a vital role in wide-ranging applications including biomedicine,nonlinear optics,and negative index metamaterials[2-4].The chiral structures of molecules and supramolecular systems may cause differential absorption of left-and right-handed circularly polarized light leading to circular dichroism(CD)activity.
