Volume 83, Number 2, July 2008
Article Number 27006
Number of page(s) 4
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 27 June 2008
EPL, 83 (2008) 27006
DOI: 10.1209/0295-5075/83/27006

Competing orders and spin-density-wave instability in La(O1-xFx)FeAs

J. Dong, H. J. Zhang, G. Xu, Z. Li, G. Li, W. Z. Hu, D. Wu, G. F. Chen, X. Dai, J. L. Luo, Z. Fang and N. L. Wang

Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences - Beijing 100190, China

received 8 May 2008; accepted in final form 30 May 2008; published July 2008
published online 27 June 2008

The interplay between different ordered phases, such as superconducting, charge or spin ordered phases, is of central interest in condensed-matter physics. The very recent discovery of superconductivity with a remarkable Tc = 26 K in Fe-based oxypnictide La(O1-xFx)FeAs (see KAMIHARA Y. et al., J. Am. Chem. Soc., 130 (2008) 3296) is a surprise to the scientific community and has generated tremendous interest. The pure LaOFeAs itself is not superconducting but shows an anomaly near 150 K in both resistivity and dc magnetic susceptibility. Here we provide combined experimental and theoretical evidences showing that a spin-density-wave (SDW) state develops at low temperature, in association with electron Nematic order. The electron-doping by F suppresses the SDW instability and induces the superconductivity. Therefore, the La(O1-xFx)FeAs offers an exciting new system showing competing orders in layered compounds.

74.70.-b - Superconducting materials.
75.30.Fv - Spin-density waves.
74.25.Jb - Electronic structure.

© EPLA 2008