Normal and superconducting properties of Co--doped BaFe$_{\mathrm{2}}$As$_{\mathrm{2}}$ and MgB$_{\mathrm{2}}$ thin films after He ion irradiation

We have investigated the normal and superconducting properties of Co-doped BaFe$_{\mathrm{2}}$As$_{\mathrm{2}}$ (Ba122) and MgB$_{\mathrm{2}}$ bridges irradiated at room temperature using a 30 kV He$+$ beam (ZEISS Orion Plus Helium ion microscope) and doses between 10$^{\mathrm{13}}$--10$^{\mathrm{17}}$/cm$^{\mathrm{2}}$. Our results show that the critical temperature of irradiated region reduces to \textless 2K for doses \textgreater 3x10$^{\mathrm{14}}$/cm$^{\mathrm{2}}$ for Ba122 and \textasciitilde 1x10$^{\mathrm{16}}$/cm$^{\mathrm{2}}$ for MgB$_{\mathrm{2}}$ films. All the samples show a consistent increase in the resistivity of irradiated region with the increase in the beam dose. Furthermore, irradiated Ba122 becomes insulating at high enough dose (6x10$^{\mathrm{16}}$/cm$^{\mathrm{2}})$ while MgB$_{\mathrm{2}}$ remains metallic at all doses used. This result for Ba122 allows us to fabricate planar SIS Josephson junction in this material; RSJ-like behavior and typical critical voltages I$_{\mathrm{c}}$R$_{\mathrm{n}}$ of 400 $\mu$ V are seen at 10 K.