Electronic states of bilayer crystals and thin films exhibiting superconductivity

日時　2025年6月18日　（水）　13：30 – 14：30
場所　放射光科学研究所　2階　セミナー室
講師　Kazuyuki Sakamoto
(Osaka University)

The decrease in dimension of a crystal from 3D bulk to 2D atomic layers often leads to the emergence of exotic physical properties. The spin-polarized electronic bands resulting from the interplay of spin-orbit coupling and the breaking of the out-of-plane inversion symmetry at solid surfaces as well as atomic layers materials formed on surfaces is one of such phenomena. Moreover, the combination of superconductivity with these spin-polarized bands has possibility to exhibit not only novel superconducting states, but also further interesting physical properties, including important concepts necessary for the realization of future quantum devices.In this talk, I will first highlight the spin-polarized electronic states of two bilayer crystals that become superconducting at low temperature, the In bilayer formed on Si(111) [1] and the Tl bilayer formed on Ag(111) [2]. The origins of the spin-polarized bands, and the effects of organic molecule adsorption to the Tc of one of these superconducting bilayer crystals will be discussed based on the experimental results obtained by ARPES and theoretical results from DFT [3,4]. I will next present the 2D-like electronic structure of a TiN film, which has a Tc of 5.2 K [5], and show its origin.

[1] T. Kobayashi et al., Phys. Rev. Lett. 125, 176401 (2020).
[2] T. Kobayashi et al., Nano Lett. 23, 7675 (2023).
[3] S. Yoshizawa et al., Nano Lett. 17, 2287 (2020).
[4] S. Inagaki et al., Phys. Rev. Materials 7, 024805 (2023).
[5] M. I. Faley et al., Nanomaterials 11, 466 (2021).

問合せ先　奥田太一、出田真一郎（放射光科学研究所）