In situ high-pressure x-ray absorption fine structure(EXAFS)measurements on the Zn K-edge in zincblende ZnS are performed up to 31.7 GPa at room temperature using a synchrotron radiation x-ray re-focused by a polycapi...In situ high-pressure x-ray absorption fine structure(EXAFS)measurements on the Zn K-edge in zincblende ZnS are performed up to 31.7 GPa at room temperature using a synchrotron radiation x-ray re-focused by a polycapillary half-lens in the classic energy-scanning transmission mode.The present XAFS data illustrate that ZnS undergoes a phase transition from zincblende F43m to rocksalt Fm3m at 16.9 GPa,accompanied by the increase of the first shell coordination number of the absorption zinc atoms and the unit-cell volume collapse of~14%.The isothermal equation of state of the F43m ZnS is well presented by the third-order Birch–Murnaghan equation of state with V0=158.6±0.8?3,B0=87±5 GPa and B0'=4(fixed).The high-pressure behavior of ZnS from the XAFS spectra is consistent with the previous high-pressure XRD results.In addition,the present experimental method demonstrates that the large divergent x-ray micro-beam induced by a polycapillary half-lens can suppress effectively the glitches from single crystal diamond anvil and improve significantly the quality of the XAFS data,which will shed light on the high-pressure XAFS applications.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
Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly s...Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral （R3c） phase of BiFeO3 first transforms to monoclinic （C2/m） phase at 7 GPa, then to orthorhombic （Pnma） phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic （Pbam） phase, indicating the coexistance of monoclinic phase with orthorhombic phase in low pressure range.展开更多
基金the National Natural Science Foundation of China under Grant Nos 11079009 and 10979060.
文摘In situ high-pressure x-ray absorption fine structure(EXAFS)measurements on the Zn K-edge in zincblende ZnS are performed up to 31.7 GPa at room temperature using a synchrotron radiation x-ray re-focused by a polycapillary half-lens in the classic energy-scanning transmission mode.The present XAFS data illustrate that ZnS undergoes a phase transition from zincblende F43m to rocksalt Fm3m at 16.9 GPa,accompanied by the increase of the first shell coordination number of the absorption zinc atoms and the unit-cell volume collapse of~14%.The isothermal equation of state of the F43m ZnS is well presented by the third-order Birch–Murnaghan equation of state with V0=158.6±0.8?3,B0=87±5 GPa and B0'=4(fixed).The high-pressure behavior of ZnS from the XAFS spectra is consistent with the previous high-pressure XRD results.In addition,the present experimental method demonstrates that the large divergent x-ray micro-beam induced by a polycapillary half-lens can suppress effectively the glitches from single crystal diamond anvil and improve significantly the quality of the XAFS data,which will shed light on the high-pressure XAFS applications.
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(10979060,11275220)
文摘Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral （R3c） phase of BiFeO3 first transforms to monoclinic （C2/m） phase at 7 GPa, then to orthorhombic （Pnma） phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic （Pbam） phase, indicating the coexistance of monoclinic phase with orthorhombic phase in low pressure range.
