Observation of bosonic resonances in GdO1−xFxFeAs by intrinsic multiple Andreev reflection effect spectroscopy

Resumo

The current–voltage characteristics and dynamic conductance spectra of Andreev arrays in nearly optimal GdO_{1 − x}F_xFeAs superconductors with the critical temperature T_c = 46–50 K have been studied. A reproducible fine structure that accompanies large gap features and caused by boson emission during the process of multiple Andreev reflections has been observed. At T = 4.2 K, the bosonic mode energy ε₀ = (12 ± 2) meV has been obtained.