Magnetic Order versus superconductivity in the Iron-based layered LaO1-xFxFeAs systems - Condensed Matter > SuperconductivityReportar como inadecuado

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Abstract: In high-transition temperature high-Tc copper oxides, it is generallybelieved that antiferromagnetism plays a fundamental role in thesuperconducting mechanism because superconductivity occurs when mobileelectrons or holes are doped into the antiferromagnetic parent compounds. Therecent discovery of superconductivity in the rare-earth R iron-based oxidesystems RO1-xFxFeAs has generated enormous interest because these materialsare the first noncopper oxide superconductors with Tc exceeding 50 K. Theparent nonsuperconducting LaOFeAs material is metallic but shows anomaliesnear 150 K in both resistivity and dc magnetic susceptibility. While opticalconductivity and theoretical calculations suggest that LaOFeAs exhibits aspin-density-wave SDW instability that is suppressed with doping electrons toform superconductivity, there has been no direct evidence of the SDW order.Here we use neutron scattering to demonstrate that LaOFeAs undergoes an abruptstructural distortion below ~150 K, changing the symmetry from tetragonalspace group P4-nmm to monoclinic space group P112-n at low temperatures,and then followed with the development of long range SDW-type antiferromagneticorder at ~134 K with a small moment but simple magnetic structure. Doping thesystem with flourine suppresses both the magnetic order and structuraldistortion in favor of superconductivity. Therefore, much like high-Tc copperoxides, the superconducting regime in these Fe-based materials occurs in closeproximity to a long-range ordered antiferromagnetic ground state. Since thediscovery of long

Autor: Clarina de la Cruz, Q. Huang, J. W. Lynn, Jiying Li, W. Ratcliff II, J. L. Zarestky, H. A. Mook, G. F. Chen, J. L. Luo, N. L. Wan


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