Enhanced superconductivity in few-layer TaS 2 due to healing by oxygenation

DOI: 10.1021/acs.nanolett.0c00871

Authors: Jonas Bekaert (University of Antwerp) , Ekaterina Khestanova (University of Manchester) , David G. Hopkinson (University of Manchester) , John Birkbeck (University of Manchester) , Nick Clark (University of Manchester) , Mengjian Zhu (University of Manchester) , Denis Bandurin (University of Manchester) , Roman Gorbachev (University of Antwerp; University of Manchester) , Simon Fairclough (University of Manchester) , Yichao Zou (University of Manchester) , Matthew Hamer (University of Manchester) , Daniel J. Terry (University of Manchester) , Jonathan J. P. Peters (University of Warwick) , Ana M. Sanchez (University of Warwick) , Bart Partoens (University of Antwerp) , Sarah Haigh (University of Manchester) , Milorad Milosevic (University of Antwerp) , Irina V. Grigorieva (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nano Letters

State: Published (Approved)
Published: April 2020
Diamond Proposal Number(s): 19315 , 21597

Abstract: When approaching the atomically thin limit, defects and disorder play an increasingly important role in the properties of two-dimensional materials. While defects are generally thought to negatively affect superconductivity in 2D materials, here we demonstrate the contrary in the case of oxygenation of ultrathin tantalum disulfide (TaS2). Our first-principles calculations show that incorporation of oxygen into the TaS2 crystal lattice is energetically favourable and effectively heals sulfur vacancies typically present in these crystals, thus restoring the electronic band structure and the carrier density to the intrinsic characteristics of TaS2. Strikingly, this leads to a strong enhancement of the electron-phonon coupling, by up to 80% in the highly-oxygenated limit. Using transport measurements on fresh and aged (oxygenated) few-layer TaS2, we found a marked increase of the superconducting critical temperature (Tc) upon aging, in agreement with our theory, while concurrent electron microscopy and electron-energy loss spectroscopy confirmed the presence of sulfur vacancies in freshly prepared TaS2 and incorporation of oxygen into the crystal lattice with time. Our work thus reveals the mechanism by which certain atomic-scale defects can be beneficial to superconductivity and opens a new route to engineer Tc in ultrathin materials.

Journal Keywords: Two-dimensional materials; transition metal dichalcogenides; superconductivity; oxygenation

Subject Areas: Materials, Physics

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E02-JEM ARM 300CF

Added On: 29/04/2020 10:52

Discipline Tags:

Surfaces Superconductors Quantum Materials Hard condensed matter - electronic properties Physics Materials Science interfaces and thin films

Technical Tags:

Microscopy Spectroscopy Electron Microscopy (EM) Electron Energy Loss Spectroscopy (EELS) Scanning Transmission Electron Microscopy (STEM)