Superfluid density of Ba(Fe$_{1-x}M_x$)$_2$As$_2$ from optical experiments

D. Wu; N. Barisic; N. Drichko; P. Kallina; A. Faridian; B. Gorshunov; M. Dressel; L. J. Li; X. Lin; G. H. Cao; Z. A. Xu

doi:10.1016/j.physc.2009.10.142

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arXiv · 0912.0849

Superfluid density of Ba(Fe$_{1-x}M_x$)$_2$As$_2$ from optical experiments

D. Wu·N. Barisic·N. Drichko·P. Kallina·A. Faridian·B. Gorshunov·M. Dressel·L. J. Li·X. Lin·G. H. Cao·Z. A. Xu

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Abstract

The temperature dependence of the $ab$-plane optical reflectivity of Ba(Fe$_{0.92}$Co$_{0.08})_2$As$_{2}$ and Ba(Fe$_{0.95}$Ni$_{0.05})_2$As$_{2}$ single crystals is measured in a wide spectral range. Upon entering the superconducting regime, the reflectivity in both compounds increases considerably at low frequency, leading to a clear gap in the optical conductivity below 100 cm$^{-1}$. From the analysis of the complex conductivity spectra we obtain the penetration depth $\lambda(T)=(3500\pm 350)$ \AA for Ba(Fe$_{0.92}$Co$_{0.08})_2$As$_{2}$ and $(3000\pm 300)$ \AA for Ba(Fe$_{0.95}$Ni$_{0.05})_2$As$_{2}$. The calculated superfluid density $\rho_s$ of both compounds nicely fits the scaling relation $\rho_s=(125\pm 25)\sigma_{dc}T_c$.

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D. Wu, N. Barisic, N. Drichko, P. Kallina, A. Faridian, B. Gorshunov, M. Dressel, L. J. Li, X. Lin, G. H. Cao, Z. A. Xu. 2009-12-04. Superfluid density of Ba(Fe$_{1-x}M_x$)$_2$As$_2$ from optical experiments. https://doi.org/10.1016/j.physc.2009.10.142

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