Klauss H-H, Luetkens H, Klingeler R, Hess C, Litterst F J, Kraken M, Korshunov M M, Eremin I, Drechsler S-L, Khasanov R, Amato A, Hamann-Borrero J, Leps N, Kondrat A, Behr G, Werner J, Büchner B
Institut für Festkörperphysik, TU Dresden, D-01069 Dresden, Germany.
Phys Rev Lett. 2008 Aug 15;101(7):077005. doi: 10.1103/PhysRevLett.101.077005. Epub 2008 Aug 14.
We present a detailed study on the magnetic order in the undoped mother compound LaFeAsO of the recently discovered Fe-based superconductor LaFeAsO1-xFx. In particular, we present local probe measurements of the magnetic properties of LaFeAsO by means of 57Fe Mössbauer spectroscopy and muon-spin relaxation in zero external field along with magnetization and resistivity studies. These experiments prove a commensurate static magnetic order with a strongly reduced ordered moment of 0.25(5)muB at the iron site below T(N)=138 K, well separated from a structural phase transition at T(S)=156 K. The temperature dependence of the sublattice magnetization is determined and compared to theory. Using a four-band spin density wave model both, the size of the order parameter and the quick saturation below T(N) are reproduced.
