2026/10/29(Thu) 14:00 -16:00 七樓研討室 7F, P7A Seminar Room
Title
Spin-polarized optical transitions probed by time- and spin-resolved ARPES
Abstract
Time- and angle-resolved photoemission spectroscopy provides direct access to the nonequilibrium dynamics of electrons in both energy and momentum space. In the first part of this seminar, I will introduce our previous pump-probe ARPES studies of the topological surface state of Sb2Te3 [1,2]. Using direct optical excitation with mid-infrared pulses, a transient asymmetric population can be generated across the Dirac cone, allowing the photoinduced surface current and its ultrafast
relaxation to be mapped in energy, momentum, and time.
I will then present our recent development of pump-probe spin-resolved ARPES at Hiroshima University. By extending time-resolved photoemission to spin detection [3], we investigate how optical excitation modifies the spin polarization of photoelectrons. In particular, I will discuss spin-polarized photoemission arising from optical transitions and how the observed spin polarization reflects the underlying transition pathways and photoemission process. These studies demonstrate how combining ultrafast excitation with spin-resolved photoemission provides a new perspective on light-induced electron and spin dynamics.
[1] K. Kuroda et al., Phys. Rev. Lett. 116, 076801 (2016). [2] K. Kuroda et al., Phys. Rev. B 95, 081103(R) (2017). [3] T. Iwata et al., Sci. Rep. 14, 127 (2024).
Language
演講語言 (Language): in English