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Superconductivity in Silicon Surface Reconstructions : Electron Transport, STM, and Control with Molecules

par Caroline CHAMPENOIS - publié le

séminaire

lundi 1er juin 2015 à 11:00, service 322 du campus Saint-Jérôme

Takashi Uchihashi
National Institute for Materials Science, Japan

Abstract
Surface reconstructions of silicon and related semiconductors with metal adatoms constitute a family of highly-ordered low dimensional materials, which are fundamentally different from their bulk counterparts. In this talk, I report on the superconductivity of Si(111)-(√7×√3)-In surface revealed by lateral electron transport measurement and scanning tunneling microscopy (STM) studies1-4). The superconducting transition was evidenced by observations of the zero resistance state and of I−V characteristics exhibiting sharp switching below 3 K. Superconducting vortices were observed by taking differential conductance (dI/dV) images using an STM at 0.5 K while magnetic field was applied. Vortices trapped along atomic steps exhibits characteristics of Josephson vortex, showing that an atomic step works as a Josephson junction. Furthermore, we found that different kinds of phthalocyanine (Pc) molecules self-assembled on the Si(111)-(√7×√3)-In surface modified its superconductivity according to their magnetic properties. This clearly shows the possibility of controlling the macroscopic superconducting properties of surface reconstructions utilizing its surface sensitivity.

1) T. Uchihashi et al., Phys. Rev. Lett. 107, 207001 (2011) [Editors’ Suggestion].
2) T. Uchihashi et al., Nanoscale Res. Lett. 8, 167 (2013).
3) S. Yoshizawa et al., J. Phys. Soc. Jap. 83, 065001 (2014).
4) S. Yoshizawa et al., Phys. Rev. Lett. 113, 247004 (2014) [Editors’ Suggestion].

Contact local : Thierry Angot

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