Volume 82, Number 6, June 2008
Article Number 67002
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 03 June 2008
EPL, 82 (2008) 67002
DOI: 10.1209/0295-5075/82/67002

Doping-dependent phase diagram of LaOMAs (M=V-Cu) and electron-type superconductivity near ferromagnetic instability

G. Xu1, W. Ming1, Y. Yao1, X. Dai1, S.-C. Zhang2 and Z. Fang1

1  Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences Beijing 100190, China
2  Department of Physics, Stanford University - Stanford, CA 94305-4045, USA

received 21 April 2008; accepted in final form 29 April 2008; published June 2008
published online 3 June 2008

By first-principles calculations, we present a doping-dependent phase diagram of the LaOMAs (M = V - Cu) family. It is characterized as a antiferromagnetic semiconductor around the LaOMnAs side and as a ferromagnetic metal around LaOCoAs. Both LaOFeAs and LaONiAs, where superconductivity were discovered, are located at the borderline of magnetic phases. An extensive Fermi surface analysis suggests that the observed superconductivity is of electron type in its origin. We discuss possible pairing mechanisms in the context of competing ferromagnetic phases found in this work and the ferromagnetic spin fluctuations.

74.70.-b - Superconducting materials.
74.25.Jb - Electronic structure.
74.25.Ha - Magnetic properties.

© EPLA 2008