Isotope effect on the transition temperature $T_c$ in Fe-based superconductors: the current status

Abstract

The results of the Fe isotope effect (Fe-IE) on the transition temperature $T_c$ obtained up to date in various Fe-based high temperature superconductors are summarized and reanalyzed by following the approach developed in [Phys. Rev. B 82, 212505 (2010)]. It is demonstrated that the very controversial results for Fe-IE on $T_c$ are caused by small structural changes occurring simultaneously with the Fe isotope exchange. The Fe-IE exponent on $T_c$ [${\alpha }_{\mathrm{Fe}}=-(\Delta T_c/T_c)/(\Delta M/M)$, $M$ is the isotope mass] needs to be decomposed into two components with the one related to the structural changes (${\alpha }_{\mathrm{Fe}}^{\mathrm{str}}$) and the genuine (intrinsic) one (${\alpha }_{\mathrm{Fe}}^{\mathrm{int}}$). The validity of such decomposition is further confirmed by the fact that ${\alpha }_{\mathrm{Fe}}^{\mathrm{int}}$ coincides with the Fe-IE exponent on the characteristic phonon frequencies ${\alpha }_{\mathrm{Fe}}^{\mathrm{ph}}$ as is reported in recent EXAFS and Raman experiments.

7 pages, 4 figures. The paper is partially based on the results published in [New J. Phys. 12, 073024 (2010) = arXiv:1002.2510] and [Phys. Rev. B 82, 212505 (2010) = arXiv:1008.4540]

References in corpus (12)

• Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
• Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)
• Anion height dependence of Tc for the Fe-based superconductor
• Superconductivity and Crystal Structures of (Ba1-xKx)Fe2As2 (x = 0 - 1)
• Substitution Effects on FeSe Superconductor
• Crystal structure and phase transitions across the metal-superconductor boundary in the SmFeAsO1-xFx (0 < x < 0.20) family
• Iron isotope effect on the superconducting transition temperature and the crystal structure of FeSe_1-x
• Absence of an appreciable iron isotope effect on the transition temperature of the optimally doped SmFeAsO_{1-y} superconductor
• Intrinsic and structural isotope effects in Fe-based superconductors
• Correlation between oxygen isotope effects on the transition temperature and the magnetic penetration depth in high-temperature superconductors close to optimal doping
• Oxygen-isotope effect on the superconducting gap in the cuprate superconductor Y_{1-x}Pr_xBa_2Cu_3O_{7-δ}
• Magnetic field dependence of the oxygen isotope effect on the magnetic penetration depth in hole-doped cuprate superconductors