Direct measurement of the absolute value of the magnetic penetration depth in two-dimensional pnictide superconductor Ca$_{10}$(Pt$_{3}$As$_{8})$[(Fe $_{1-x}$ Pt$_{x})_{2}$As$_{2}$]$_{5}$

We have measured the absolute value of the magnetic penetration depth $\lambda $ in a single crystal of the Ca$_{10}$(Pt$_{3}$As$_{8})$[(Fe $_{1-x}$ Pt$_{x})_{2}$As$_{2}$]$_{5}$ (``10-3-8'') superconductor using low temperature magnetic force microscopy (MFM). We directly probed local values of $\lambda $ in the ``10-3-8'' sample using Meissner response measurements and compared Meissner curves to those obtained in a Nb reference sample. The Meissner response measured at different locations on the sample shows similar behavior indicating homogeneity of the superconducting state, in accord with tunnel-diode resonator measurements. We also discuss larger values of $\lambda $ in 10-3-8 relative to $\lambda $ values measured in other pnictide systems.