The Open Condensed Matter Physics Journal

2008, 1 : 13-18
Published online 2008 November 03. DOI: 10.2174/1874186X00801010013
Publisher ID: TOCMPJ-1-13

RESEARCH ARTICLE
 A Possible Pairing Mechanism in Fe-Based High Temperature Superconductors

Ning Chen and Yang Li, *
Department of Engineering Science and Materials, University of Puerto Rico at Mayaguez, Mayaguez PR 00681-9044, USA
School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
Department of physics, University of Science and Technology Beijing, Beijing 100083, China

* Address correspondence to this author at the Department of Engineering Science and Materials, University of Puerto Rico at Mayaguez, Mayaguez PR 00681-9044, USA; E-mail: and ylibp@hotmail.com

ABSTRACT

The electronic structures of LaOFeAs superconductors with antiferromagnetic model were simulated by using the first-principle method. The calculated density of states (DOS) reveals that some antiferromagnetic energy peaks are splitted due to the hybridization of Fe-3d and As-4p on the FeAs layer. The calculated spin moment for LaOFeAs is 2.39 μB/Fe. The band structure and DOS around the Fermi level suggest this compound with a semimetal-like characteristic. Beside on the Fe, a spin polarization occurs on the As site, which is distributed with both As-4p and As-4s orbitals. A unique electronic structure is found to be associated with the deep inner orbital coupling in the LaOFeAs compound, which provides an independent energy band with a high vibration frequency. The two bands with deep inner orbital coupling as well as the spin polarization of As-4s could be used to explain some behaviours of carrier pairing in the superconducting state. In addition, the simulation also was performed on a series of F-doped LaOFeAs with different fluorine composition. The results show with F-doping increasing the spin polarization of As decreasing. Superconductivity will be suppressed by the heavy F-doping concentration