ISMO

Institut des Sciences Moléculaires d'Orsay

Partenaires

CNRS UPS

lundi 29 avril


Mise à jour
samedi 27 avril

Accueil > Séminaires > Année 2023 > Séminaire de Kazuki Sumida (4 oct)

Séminaire de Kazuki Sumida (4 oct)

Hiroshima Synchrotron Radiation Center

par Martrenchard-Barra Séverine - 24 septembre 2023

Laser-based angle-resolved photoemission spectroscopy on topological insulators

Unveiling the electronic structure in solids is important because it is closely related not only to exotic quantum properties of condensed matter but also to numerous functionalities associated with device applications. Angle-resolved photoemission spectroscopy (ARPES) has been widely recognized as one of the leading experimental probes due to its energy and momentum resolution capability. Over the past few decades, the resolution of ARPES has improved dramatically. One of the catalysts for this improvement was the introduction of lasers as a light source.
In this talk, I will present two unique results of laser-based ARPES on topological insulators (TIs). The first topic is the surface-termination-dependent electronic structure of PbBi4Te4S3 revealed by a 6 eV laser-based spin-resolved ARPES system with micrometer spatial resolution recently developed at Hiroshima University [1,2]. Utilizing a well-focused laser (<10 μm), we have successfully observed two distinguishable spin-polarized Dirac-cone-like surface states originating from the different terminations.
The second topic is the ultrafast carrier dynamics of TIs. We have performed time-resolved ARPES for (Sb,Bi)2Te3 using 1.5 eV (pump) and 6.0 eV (probe) femtosecond laser pulses at ISSP, University of Tokyo [3,4]. Our time-resolved ARPES studies have disclosed several functions, such as >400-ps prolonged duration, population inversion, and surface photovoltage effect, on the nonequilibrated surface of TIs.

References
[1] K. Sumida et al., Phys. Rev. Materials 2, 104201 (2018).
[2] T. Iwata et al., arXiv:2305.14052.
[3] K. Sumida et al., Sci. Rep. 7, 14080 (2017).
[4] K. Sumida et al., Prog. Surf. Sci. 96, 100628 (2021).

Dans la même rubrique :