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Superconductivity Induced by Oxygen Doping in Y2 O2 Bi.
Xiyue Cheng1, Elijah E Gordon2, Myung-Hwan Whangbo1,2
1State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou, 350002, China.
Angewandte Chemie (International Ed. in English)
|April 4, 2017
Summary
Oxygen doping transforms Y2O2Bi into a superconductor. This study identifies oxygen
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Layered Y2O2Bi exhibits superconductivity upon doping with oxygen.
- This phenomenon raises critical questions regarding oxygen's location, the underlying superconducting mechanism, and strategies for novel superconductor discovery.
Purpose of the Study:
- To investigate the preferred sites for oxygen incorporation in Y2O2Bi.
- To elucidate the electronic structure modifications induced by oxygen doping.
- To explore the implications for superconductivity within the 'flat/steep' band model.
Main Methods:
- First-principles calculations were employed for both undoped and oxygen-doped Y2O2Bi.
- Analysis focused on atomic site preference and electronic band structure alterations.
Main Results:
- Oxygen atoms preferentially occupy the centers of Bi4 squares within the Bi square net.
- Oxygen doping elevates the energy of specific Bi 6p x/y bands due to the formation of antibonding interactions with oxygen 2p x/y orbitals.
- These electronic changes satisfy the conditions for the 'flat/steep' band model, crucial for superconductivity.
Conclusions:
- The study pinpoints specific interstitial sites for oxygen in Y2O2Bi.
- It establishes a direct link between oxygen doping, electronic band structure modifications, and the emergence of superconductivity.
- The findings provide insights into designing new superconductors based on band engineering.