中文 |

Research Progress

Researchers Uncover the Mechanism of Oxygen Doping Induced Superconductivity

Nov 15, 2017

Microscopic superconductivity mechanism of superconductors, one of the important functional materials, has remained a challenge. Recent experiments found that the layered Y2O2Bi becomes a superconductor if oxygen atoms were incorporated into the material. This phenomenon was considered as of a possible topological superconductivity. However, where the doped oxygen locates and the mechanism of superconductivity are unclear.

In a study published in Angew. Chem. Int. Ed., the research group led by Prof. DENG Shuiquan from Fujian Institute of Research on the Structure of Matter (FJIRSM) of Chinese Academy of Sciences (CAS) reported a microscopic superconductivity mechanism induced by oxygen doping.

On the basis of density functional theory (DFT) calculations, the centres of Bi4 squares in the Bi square nets were found by researchers to be the energetically most favourable positions for the doped oxygen atoms which lead to the formation of [OY2B4] polyhedra.

The electronic structure calculations showed a notable difference between the undoped Y2O2Bi and oxygen-doped Y2O2.125Bi: the raising of Bi 6p x/y bands. This was caused by the weak antibonding interactions between the doped O 2p orbitals and the Bi 6p orbitals.

Once oxygen doped, the Fermi level was found to cross the bottom of the raised Bi 6p x/y bands. Therefore, the steep and flat band occur around the Fermi level, which lead to the condition for the “flat/steep” band model of superconductivity.

The [OY2B4] polyhedron acts as a “functional motif” which creates the structural condition for the superconductivity.

This study revealed the mechanism of superconductivity for layered Y2O2Bi and provides practical guidelines for discovering new superconductors.

This work was supported by the Strategic Priority Research Program of the CAS, National Key Research and Development Program of China, 973 Program of China and 100 Talents Program of CAS and Fujian Province.

 

The raising of Bi 6p x/y bands duo to the doped oxygen. (Image by Prof. DENG’s Group) 

Contact Us
  • 86-10-68597521 (day)

    86-10-68597289 (night)

  • 86-10-68511095 (day)

    86-10-68512458 (night)

  • cas_en@cas.cn

  • 52 Sanlihe Rd., Xicheng District,

    Beijing, China (100864)

Copyright © 2002 - Chinese Academy of Sciences