Welcome to Cheng-Tai Kuo's website! The current projects are as follows:
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Layer/Element-Resolved Electronic Structure
Layer/Element-Resolved Electronic Structure
X-ray photoemission spectroscopy (XPS) and angle-resolved photoemission spectroscopy (ARPES) are powerful techniques for visualizing the electronic structure in materials. Combining standing wave (SW) excitation and XPS/ARPES, it allows us to derive additional information, such as the spatial distribution of composition and the layer/element- specific electronic structure of multialyers/crystals.
A SW with its iso-intensity planes parallel to the diffracting planes is created by the interference between the incident and diffracted waves. When the incidence angle moves from below to above the Bragg condition, the SW was shifted by half of the wavelength with respect to the diffracting planes. Depending on the locations of the atoms, the incidence-angle dependence of the core-level photoelectron intensities will show distinct modulations. Additionally, the obtained layer-resolved densities of states (DOS) can be directly compared to the density functional theory.
Phys. Rev. B 98, 155133 (2018),
Phys. Rev. B 98, 165124 (2018),
Nature Communcations 9, 3306 (2018)
Depth-Resolved Resonant Inelastic X-Ray Scattering
Depth-Resolved Resonant Inelastic X-Ray Scattering
Resonant inelastic x-ray scattering (RIXS) is a photon-in/photon-out synchrotron-based spectroscopy that has been shown to uniquely probe the charge transfer, dd, magnetic, phonon, and other excitations in correlated oxides and other systems. RIXS is considered to be a probe of bulk properties, and it would thus be desirable to give RIXS more quantitative depth sensitivity.
Combining standing wave (SW) excitation with resonant inelastic x-ray scattering (RIXS) can lead to depth resolution and interface sensitivity for studying orbital and magnetic excitations in correlated oxide heterostructures. For example, for the multilayer heterostructures consisting of a superconductor La1.85Sr0.15CuO4 (LSCO) and a half-metallic ferromagnet La0.67Sr0.33MnO3 (LSMO), the magnetic excitations are found to arise from the interfaces. SW-RIXS measurements should provide unique layer-resolved insights concerning their orbital and magnetic excitations, as well as a challenge for RIXS theory to specifically deal with interface effects.
Phys. Rev. B 98, 235146 (2018)
Phys. Rev. Mater. 4, 115002 (2020)
Contact
SSRL/SLAC2575 Sand Hill Road, Mail Stop 99Menlo Park, CA 94025, USAOffice: +1(650)-965-3872Email: ctkuo[at]SLAC.Stanford.edu
SSRL/SLAC2575 Sand Hill Road, Mail Stop 99Menlo Park, CA 94025, USAOffice: +1(650)-965-3872Email: ctkuo[at]SLAC.Stanford.edu
Last updated on 09/02/2019
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