15:30 〜 16:00
[SIT21-06] High spatial resolution electronic structure analysis by scanning transmission electron microscopy and electron energy loss spectroscopy
★Invited Papers
キーワード：走査型電子顕微鏡、電子エネルギー損失分光法
Since transition metal (TM) oxides exhibit a variety of physical properties, which are sensitively related to their complex crystal structures and constituent elements, many experimental and theoretical studies has been conducted for not only bulk but also thin film. In particular, the relationship between localized TM d-band and oxygen 2p band is one of the key factors to control of the property. For further understanding, it is important to examine individual electronic structure with atomic resolution. This is because it has often some nonequivalent atomic sites in a unit cell even a single crystal, and they have different electronic structure for the same element.
In the field of high spatial resolution analysis, scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) is the one way to know both elemental and electronic structure with atomic scale. However, while this technique can offer elemental and electronic state mapping with atomic resolution, it is, in principle, difficult to experimentally extract the information with truly atomic resolution due to the physically limited spatial resolution caused by the delocalization of inelastic scattering electrons1 although sub-Å size electron probe has achieved thanks to the development spherical aberration corrector. Therefore, the interpretation of STEM-EELS with atomic scale is not simple, and careful attention of the mixing of signals from neighboring atomic-columns is required.
In our previous researches, we focus on electronic structure of oxygen 2p band and transition metal 3d band with high spatial resolution for transition metal oxide which has layered structure. Since the fine structure of O K-edge reflects the unoccupied 2p state which hybridized with cation electronic orbital due to its covalent bonding character, it includes much information about chemical bond. In the presentation, I will introduce some applications of high spatial resolution STEM-EELS combined with some theoretical calculations.
In the field of high spatial resolution analysis, scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) is the one way to know both elemental and electronic structure with atomic scale. However, while this technique can offer elemental and electronic state mapping with atomic resolution, it is, in principle, difficult to experimentally extract the information with truly atomic resolution due to the physically limited spatial resolution caused by the delocalization of inelastic scattering electrons1 although sub-Å size electron probe has achieved thanks to the development spherical aberration corrector. Therefore, the interpretation of STEM-EELS with atomic scale is not simple, and careful attention of the mixing of signals from neighboring atomic-columns is required.
In our previous researches, we focus on electronic structure of oxygen 2p band and transition metal 3d band with high spatial resolution for transition metal oxide which has layered structure. Since the fine structure of O K-edge reflects the unoccupied 2p state which hybridized with cation electronic orbital due to its covalent bonding character, it includes much information about chemical bond. In the presentation, I will introduce some applications of high spatial resolution STEM-EELS combined with some theoretical calculations.