Nodeless multiband superconductivity in stoichiometric single crystalline CaKFe${}_4$As${}_4$

Kyuil Cho, A. Fente, S. Teknowijoyo +9

Measurements of the London penetration depth and tunneling conductance in single crystals of the recently discovered stoicheometric, iron - based superconductor, CaKFe${}_4$As${}_4$ (C…