TY - JOUR
T1 - Crystal structure and phase transitions across the metal-superconductor boundary in the SmFeAsO1-xFx (0≤x≤0.20) family
AU - Margadonna, Serena
AU - Takabayashi, Yasuhiro
AU - McDonald, Martin T.
AU - Brunelli, Michela
AU - Wu, G.
AU - Liu, R. H.
AU - Chen, X. H.
AU - Prassides, Kosmas
PY - 2009/1/5
Y1 - 2009/1/5
N2 - The fluorine-doped rare-earth iron oxyarsenides REFeAsO1-x Fx (RE=rare earth) have recently emerged as a new family of high-temperature superconductors with transition temperatures (Tc) as high as 55 K. Here we use high-resolution synchrotron x-ray diffraction to study the structural properties of SmFeAsO1-x Fx (0≤x≤0.20) in which superconductivity emerges near x∼0.07 and Tc increases monotonically with doping up to x∼0.20. We find that orthorhombic symmetry survives through the metal-superconductor boundary well into the superconducting regime and the structural distortion is only suppressed at doping levels, x≥0.15, when the superconducting phase becomes metrically tetragonal. Remarkably this crystal symmetry crossover coincides with reported drastic anomalies in the resistivity and the Hall coefficient, and a switch of the pressure coefficient of Tc from positive to negative, thereby implying that the low-temperature structure plays a key role in defining the electronic properties of these superconductors.
AB - The fluorine-doped rare-earth iron oxyarsenides REFeAsO1-x Fx (RE=rare earth) have recently emerged as a new family of high-temperature superconductors with transition temperatures (Tc) as high as 55 K. Here we use high-resolution synchrotron x-ray diffraction to study the structural properties of SmFeAsO1-x Fx (0≤x≤0.20) in which superconductivity emerges near x∼0.07 and Tc increases monotonically with doping up to x∼0.20. We find that orthorhombic symmetry survives through the metal-superconductor boundary well into the superconducting regime and the structural distortion is only suppressed at doping levels, x≥0.15, when the superconducting phase becomes metrically tetragonal. Remarkably this crystal symmetry crossover coincides with reported drastic anomalies in the resistivity and the Hall coefficient, and a switch of the pressure coefficient of Tc from positive to negative, thereby implying that the low-temperature structure plays a key role in defining the electronic properties of these superconductors.
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U2 - 10.1103/PhysRevB.79.014503
DO - 10.1103/PhysRevB.79.014503
M3 - Article
AN - SCOPUS:58949094904
VL - 79
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
SN - 0163-1829
IS - 1
M1 - 014503
ER -