Superconducting and topological band structures visualized by photoemission spectroscopy

The momentum-resolved band structure provides fundamental information to understand the electronic properties of materials. The angle-resolved photoemission spectroscopy (ARPES) is the most powerful technique to visualize the band structure by mapping the intensities of photoelectrons as a function of angle and energy. With the spin-resolved technique, we can also identify the spin-polarized character of the band. In addition, the time-resolved ARPES with a pump-probe technique can track the reordering process of the electron system from its nonequilibrium state. In this project, we utilize these various ARPES techniques and study the following condensed matter physics: nonconventional superconductors, heavy fermions, strongly correlated systems, topological quantum phases, and quantum well states. The state-of-art equipment using a laser source capable of high energy and momentum resolutions enable us to precisely identify even subtle electronic features close to the Fermi level, such as an energy gap of superconductor and a mode-coupled dispersion, which yield exotic behaviors of quantum materials.

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