Special CMSM Seminar No.306

Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique for directly visualizing electronic structures in solids. By combining ARPES with a pump-probe scheme using a femtosecond laser, time-resolved ARPES (TARPES) enables direct observation of nonequilibrium electronic structures and ultrafast carrier dynamics with femtosecond time resolution. In this seminar, I will first introduce the basic principles of photoemission spectroscopy and pump-probe two-photon photoemission processes used in TARPES measurements. I will then present several recent studies on topological materials investigated by TARPES, including long-lived nonequilibrium Dirac fermions in bulk-insulating topological insulators, magnetic-impurity-induced modifications of ultrafast carrier dynamics, and spin-texture-dependent suppression of resonant interband transitions in topological surface states. Finally, I will briefly discuss future prospects of ultrafast spin-resolved photoemission spectroscopy for investigating light-induced phenomena and nonequilibrium quantum states in topological materials.

Keisuke MASUDA
Spin Theory Group
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