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Effect of pressure on the superconducting and spin-density-wave states of SmFeAsO 1 − x F x

2008; American Physical Society; Volume: 78; Issue: 1 Linguagem: Inglês

10.1103/physrevb.78.012505

1550-235X

B. Lorenz, Kalyan Sasmal, R. P. Chaudhury, Xianhui Chen, Ronghua Liu, Tom Wu, C. W. Chu,

Physics of Superconductivity and Magnetism

High-temperature superconductors with a ${T}_{c}$ above 40 K have been found to be strongly correlated electron systems and to have a layered structure. Guided by these rules, Kamihara et al. [J. Am. Chem. Soc. 130, 3296 (2008)] discovered a ${T}_{c}$ up to 26 K in the layered $\text{La}({\text{O}}_{1\ensuremath{-}x}{\text{F}}_{x})\text{FeAs}$. By replacing La with trivalence rare-earth (RE) elements of smaller ionic radii, ${T}_{c}$ has subsequently been raised to 41--52 K. Many theoretical models have been proposed that emphasize the important magnetic origin of superconductivity in this compound system and a possible further ${T}_{c}$ enhancement in $\text{RE}({\text{O}}_{1\ensuremath{-}x}{\text{F}}_{x})\text{FeAs}$ by compression. This later prediction appears to be supported by the pressure-induced ${T}_{c}$ increase in $\text{La}({\text{O}}_{0.89}{\text{F}}_{0.11})\text{FeAs}$ observed. Here we show that, in contrast to previous expectations, pressure can either suppress or enhance ${T}_{c}$, depending on the doping level, suggesting that a ${T}_{c}$ exceeding 50 K may be found only in the yet-to-be discovered compound systems related to but different from $\text{RE}({\text{O}}_{1\ensuremath{-}x}{\text{F}}_{x})\text{FeAs}$ and that the ${T}_{c}$ of $\text{La}({\text{O}}_{1\ensuremath{-}x}{\text{F}}_{x})\text{FeAs}$ and $\text{Sm}({\text{O}}_{1\ensuremath{-}x}{\text{F}}_{x})\text{FeAs}$ may be further raised to about 50 K.