Abstract
Among the iron-based superconductors, "122"-type compounds have been widely studied due to the availability of high-quality single crystals. However, due to lack of a natural cleavage plane, the cleaved surface is usually polarized, which allows doping change or structure modification on the surface. In this paper, we propose a simple method to successfully transform the 122-type parent compound BaFe2As2 to a superconductor via room-temperature relaxation or uniaxial strain. Using scanning tunneling microscopy/spectroscopy, we demonstrate that this superconductivity results directly from the disordered surface morphologies. Based on the transport results and the disappearance of superconductivity with every new cleave, we conclude that the superconductivity only manifests at the most superficial surface. Our finding opens up an unexpected way to achieve superconductivity in undoped BaFe2As2, other than chemical doping, which may offer an alternative channel to understand the iron-based superconductivity and its connection with disorders.
| Original language | English |
|---|---|
| Article number | 034801 |
| Journal | Physical Review Materials |
| Volume | 7 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2023 |
| Externally published | Yes |
Funding
The work at IOP is supported by grants from the National Natural Science Foundation of China (Grants No. 2019000043, No. 111920101005, No. 11888101, No. 11234014, No. 61888102, No. 11920101005, and No. 11921004), the Ministry of Science and Technology of China (Grants No. 2021ZD0302700, No. 2016YFA0202300, No. 2018YFA0305700, No. 2017YFA0302900, and No. 2019YFA0308500), and the Chinese Academy of Sciences (Grants No. BR201902, No. 2020000053, No. XDB28000000, No. XDB07000000, and No. 112111KYSB20160061). This work is partially supported by the Synergic Extreme Condition User Facility, Beijing, China.