Ion-Selective Scattering Studied Using the Variable-Energy Electron Irradiation in the Ba0.2K0.8Fe2As2 Superconductor

Low-temperature variable-energy electron irradiation was used to induce non-magnetic disorder in a single crystal of a hole-doped iron-based superconductor, Ba1-xKxFe2As2, x = 0.80. To avoid systematic errors, the beam energy was adjusted non-consequently for five values between 1.0 and 2.5 MeV when sample resistance was measured in situ at 22 K. For all energies, the resistivity raises linearly with the irradiation fluence suggesting the creation of uncorrelated dilute point-like disorder (confirmed by simulations). The rate of the resistivity increase peaks at energies below 1.5 MeV. Comparison with calculated partial cross-sections points to the predominant creation of defects in the iron sublattice. Simultaneously, superconducting Tc, measured separately between the irradiation runs, is monotonically suppressed as expected, since it depends on the total scattering rate, hence on the total cross-section, which is a monotonically increasing function of the energy. Our work experimentally confirms an often-made assumption of the dominant role of the iron sub-lattice in iron-based superconductors.

Automated summary

Low-temperature variable-energy electron irradiation induced non-magnetic disorder in a hole-doped iron-based superconductor Ba1-xKxFe2As2, x = 0.80. The resistivity of the sample increased linearly with irradiation fluence, indicating the creation of uncorrelated dilute point-like disorder. The predominant creation of defects in the iron sublattice was confirmed by comparing with calculated partial cross-sections. Simultaneously, the superconducting transition temperature was monotonically suppressed due to the total scattering rate, supporting the assumption of the dominant role of the iron sub-lattice in iron-based superconductors.