With Tc values up to 55 K, the Fe arsenides have attracted considerable recent attention. The key structural element appears to be a square planar arrangement of Fe ions, tetrahedrally coordinated by As, as exemplified by BaFe2As2 shown above. Parent compounds are antiferromagnetic, with a coupled orthorhombic distortion, but suppression of the long range magnetic order leads to superconducting behavior (as illustrated for the case of Co-doping above). Related phosphides are either paramagnetic (BaFe2P2) or superconducting (LaFePO). Our research seeks to address the nature of the magnetic, "nematic", and superconducting states in these families of compounds, and to explore the range of occurrence of superconductivity. Experiments emphasize magnetotransport and quantum oscillations to determine Fermi surface topology and quasiparticle properties, and the use of uniaxial strain as a probe of the nematic behavior.
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|Fisher Research Group
Geballe Laboratory for Advanced Materials
Dept. of Applied Physics
|Last Updated: Jan 4th 2015|