Abstract
The phenomenon of oxygen incorporation-induced superconductivity in iron telluride (Fe1+yTe, with antiferromagnetic (AFM) orders) is intriguing and quite different from the case of FeSe. Until now, the microscopic origin of the induced superconductivity and the role of oxygen are far from clear. Here, by combining in situ scanning tunneling microscopy/spectroscopy (STM/STS) and X-ray photoemission spectroscopy (XPS) on oxygenated FeTe, we found physically adsorbed O2 molecules crystallized into c (2/3 × 2) structure as an oxygen overlayer at low temperature, which was vital for superconductivity. The O2 overlayer were not epitaxial on the FeTe lattice, which implied weak O2 –FeTe interaction but strong molecular interactions. The energy shift observed in the STS and XPS measurements indicated a hole doping effect from the O2 overlayer to the FeTe layer, leading to a superconducting gap of 4.5 meV opened across the Fermi level. Our direct microscopic probe clarified the role of oxygen on FeTe and emphasized the importance of charge transfer effect to induce superconductivity in iron-chalcogenide thin films.
Highlights
Iron-chalcogenide Fe (Se,Te) superconductors are an important family of (Tc) ironbased high transition temperature (Tc) superconductors
Yamazaki et al [19] and Sun et al [18] have studied the dynamics of oxygen annealing and concluded that the superconductivity first emerged on the surface and the superconducting regions moved inside with non-superconducting materials left on the surface, such as Fe2O3, TeOx, FeTe2
We have systematically investigated the changes of morphology and electronic structure of 10UC FeTe films after O2 adsorption
Summary
Iron-chalcogenide Fe (Se,Te) superconductors are an important family of (Tc) ironbased high transition temperature (Tc) superconductors. Superconductivity could be induced in FeTe through Se or S substitution [10] and oxygen incorporation by low-temperature annealing or long-time exposure in an O2 atmosphere [11,12,13,14,15,16,17,18,19,20,21]. The controversial results from different experimental probes call for a unified study of the crystal, chemical and electronic structures on thin films with controlled oxygen incorporation. This is generally challenging to achieve for ex situ measurements because samples exposed to the atmosphere inevitably change surface morphology and chemistry. We overcame this challenge by integrating one ultra-high vacuum environment for the sample growth and oxygenation process along with spectroscopic tools with elemental and spatial resolution
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
