Transport, magnetic and optical investigations on EuRbFe4As4 single crystals evidence that the ferromagnetic ordering of the Eu2+ magnetic moments at TN=15 K, below the superconducting transition (Tc=36 K), affects superconductivity in a weak but intriguing way. Upon cooling below TN, the zero resistance state is preserved and the superconductivity is affected by the in-plane ferromagnetism mainly at domain boundaries; a perfect diamagnetism is recovered at low temperatures. The infrared conductivity is strongly suppressed in the far-infrared region below Tc, associated with the opening of a complete superconducting gap at 2Δ=10 meV. A gap smaller than the weak coupling limit suggests the strong orbital effects or, within a multiband superconductivity scenario, the existence of a larger yet unrevealed gap.
@article{arxiv.1807.04135,
title = {Unique interplay between superconducting and ferromagnetic orders in EuRbFe$_4$As$_4$},
author = {V. S. Stolyarov and A. Casano and M. A. Belyanchikov and A. S. Astrakhantseva and S. Yu. Grebenchuk and D. S. Baranov and I. A. Golovchanskiy and I. Voloshenko and E. S. Zhukova and B. P. Gorshunov and A. V. Muratov and V. V. Dremov and L. Ya. Vinnikov and D. Roditchev and Y. Liu and G. -H. Cao and M. Dressel and E. Uykur},
journal= {arXiv preprint arXiv:1807.04135},
year = {2018}
}