Структура и анизотропия сверхпроводящего параметра порядка Ba0.65K0.35Fe2As2 методом андреевской спектроскопии
The superconducting order parameters in optimally doped Ba0.65K0.35Fe2As2 single crystals have been directly measured using multiple Andreev reflection effect spectroscopy of superconductor–normal metal–superconductor break-junctions. We determine two superconducting gaps, which are nodeless in the kx-ky-plane of the momentum space, and resolve a substantial in-plane anisotropy of the large gap. The temperature dependences of the gaps indicate a strong coupling within the bands where develops, a weak coupling in the condensate with the small gap , and a moderate interband interaction between the two condensates. The own critical temperatures of both condensates have been estimated (under the hypotherical assumption of zero interband interaction).