Yukio Hasegawa

Affiliation: The Institute for Solid State Physics, University of Tokyo

Research Interests: surface science, nanoscale science, scanning tunneling microscopy, superconductivity, STM

Title: Scanning tunnel microscopy on quantum phase transition in atomic layer two-dimensional superconductivity
Abstract: Scanning tunnel microscopy (STM) provides atomically resolved images showing not only the atomic structure of the surfaces, but also their electronic states. Therefore, this technique allows us to observe and evaluate the size effect of vortex formation in nanosized superconductors and the superconducting proximity effect by directly probing the local superconducting gaps and creating images showing their spatial distribution.
In this talk, I present our recent efforts to reveal various unique phenomena that occur in atomically thin two-dimensional (2D) superconductors. 2D superconductors are known to exhibit a superconducting-insulator transition (SIT) at absolute zero temperature by introducing disorder or applying a magnetic field. However, recent studies on atomically thin highly crystalline superconductors have revealed the presence of metallic states intervened between the two phases, which stimulated discussion on the origin of the metallic state and related phenomena on the quantum critical transition. I discuss the possible mechanism of the phase through STM observation of the phase.