Optical and transport properties of Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ films

Yurii A. Aleshchenko; Andrey V. Muratov; Elena S. Zhukova; Lenar S. Kadyrov; Boris P. Gorshunov; Giovanni A. Ummarino; Ilya A. Shipulin

doi:10.1016/j.solidstatesciences.2024.107787

paper

Optical and transport properties of Ba(Fe $_{1 - x}$ Ni $_{x}$ ) $_{2}$ As $_{2}$ films

arXiv:2412.11895 · doi:10.1016/j.solidstatesciences.2024.107787

Abstract

The broad-band optical spectroscopy was used to study the optical and the hidden transport properties of the Ba(Fe $_{1 - x}$ Ni $_{x}$ ) $_{2}$ As $_{2}$ superconducting films with different Ni contents. The normal state data were analyzed using a Drude-Lorentz model with two Drude components: narrow and broad ones. In the superconducting state, two gaps with $2 Δ_{0}^{(1)} / k_{B} T_{c} = 1.57$ and $2 Δ_{0}^{(2)} / k_{B} T_{c} = 3.48$ are formed for the Ba(Fe $_{0.965}$ Ni $_{0.035}$ ) $_{2}$ As $_{2}$ films, while for the Ba(Fe $_{0.95}$ Ni $_{0.05}$ ) $_{2}$ As $_{2}$ films these characteristic ratios are 1.88--2.08 and 3.66--4.13. Both gaps are formed from the narrow Drude component, whereas the broad Drude component remains ungapped. The calculated from infrared data total dc resistivity of the films with Ni contents $x = 0.05$ and $x = 0.08$ as well as the low-temperature scattering rate for the narrow Drude component show a hidden Fermi-liquid behavior. On the contrary, the films with $x = 0.035$ manifest a hidden non-Fermi-liquid behavior. The Allen theory generalized to a multiband systems was applied to the analysis of the temperature dependences of a resistivity of the Ba(Fe $_{1 - x}$ Ni $_{x}$ ) $_{2}$ As $_{2}$ films. The change of total electron-boson coupling and representative energy in the normal state versus the superconducting state for this system was shown to be typical of other iron-based superconducting materials as well as high-temperature superconducting cuprates.

27 pages, 10 figures, 2 tables

Optical and transport properties of Ba(Fe1−x​Nix​)2​As2​ films

Abstract

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Optical and transport properties of Ba(Fe $_{1 - x}$ Ni $_{x}$ ) $_{2}$ As $_{2}$ films