Synthesis and HRTEM Investigation of EuRbFe4As4 Superconductor
A. Yu. Degtyarenko, Igor A. Karateev, А. В. Овчаров, В. А. Власенко, K. S. Pervakov
Abstract
In the stoichiometric iron-based superconductor EuRbFe4As4, superconductivity coexists with a long-range magnetic ordering in Eu layers. Using high-resolution transmission electron microscopy (HRTEM), we observed an atomic structure of as-grown EuRbFe4As4 crystals. HRTEM shows that crystals have two-dimensional intrinsic nanoinclusions established to be the RbFe2As2 (122) phase with a volume fraction of ~5.6%. In contrast with the CaKFe4As4 compound, similar inclusions are not superconducting down to 2 K, and no second magnetization peak was observed in the magnetization measurements at low temperature with B ‖ ab. We show that the non-superconducting 122 phase nanoinclusions could act as 2D pinning centers.