Elucidating the peculiar properties of inversion-symmetry-broken surface superconductors with scanning tunneling microscopy

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H05453
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Condensed matter physics I
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Hirahara Toru 東京工業大学, 理学院, 准教授 (30451818)
• Research Collaborator: TANAKA Tomoaki ; YOSHINO Ryo ; AKIYAMA Kenta
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 超伝導 / 走査トンネル顕微鏡 / ラシュバ効果

Outline of Final Research Achievements

We report the relationship between the surface superstructure of SrTiO3(001) (STO) substrate
and superconducting properties of single unit cell (1 UC) FeSe films using scanning tunneling
microscopy/spectroscopy (STM/STS). Under reflection high-energy-electron diffraction (RHEED) observation, we controlled the periodicity of the STO surface to 2×1 and √2×√2 by changing the annealing temperature and grew high-quality FeSe films. We found that the substrate periodicity can be imaged through the 1 UC FeSe from high-resolution STM observations and obtained clear evidence that the superconducting gap size depends on the surface periodicity (10-15 meV on 2×1 and 15-17.5 meV on √2×√2) for the first time. The results are discussed in terms of the surface termination of the STO substrate.

Free Research Field

表面・ナノ物性