Superconducting order parameter of the RbCa$_2$Fe$_4$As$_4$F$_2$ compound

The superconducting order parameter of the RbCa$_2$Fe$_4$As$_4$F$_2$ compound belonging to the new 12442 family of iron-based superconductors with a critical temperature of $T_c\sim32\,$K has been studied. Two superconducting condensates with the order parameters $\Delta_L\sim6.3\,$meV and $\Delta_S\sim2.8\,$meV have been detected for the first time by multiple Andreev reflection spectroscopy. The temperature dependence of the superconducting critical current density $J_c(T)$ in the intrinsic field has been measured. The approximation of the dependence $J_c(T)$ demonstrates the correspondence of the experimental data to the double-gap model with the $s$-wave order parameter and the gaps of $\Delta_L\sim6\,$meV and $\Delta_S\sim2\,$meV. The superconducting order parameters obtained by two different methods are in good agreement with each other.