Marsik, Premysl Kim, Kyung Wan Dubroka, Adam Rössle, Matthias Malik, Vivek Kumar Schulz, Leander Wang, Chen Nan Niedermayer, Ch. Drew, Alan J. Willis, M. Wolf, T. Bernhard, Christian 2001-07-27 We report muon spin rotation (μSR) and infrared spectroscopy experiments on underdoped BaFe_1.89Co_0.11As₂ which show that bulk magnetism and superconductivity (SC) coexist and compete on the nanometer length scale. Our combined data reveal a bulk magnetic order, likely due to an incommensurate spin density wave (SDW), which develops below T^mag≈32  K and becomes reduced in magnitude (but not in volume) below T_c=21.7  K. A slowly fluctuating precursor of the SDW seems to develop already below the structural transition at T^s≈50  K. The bulk nature of SC is established by the μSR data which show a bulk SC vortex lattice and the IR data which reveal that the majority of low-energy states is gapped and participates in the condensate at T≪T_c. application/pdf https://folia.unifr.ch/global/documents/301659 https://folia.unifr.ch/documents/301659/files/ber_ccm.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevLett.105.057001 info:eu-repo/semantics/openAccess License undefined Physical Review Letters. - 2010, vol. 105, no. 5, p. 057001 info:eu-repo/classification/udc/53 Coexistence and Competition of Magnetism and Superconductivity on the Nanometer Scale in Underdoped BaFe_1.89Co_0.11As₂ http://purl.org/coar/resource_type/c_6501