Superconductivity in the system $\mathrm{M}{\mathrm{o}}_{\mathrm{x}}{\mathrm{C}}_{\mathrm{y}}\mathrm{G}{\mathrm{a}}_{\mathrm{z}}{\mathrm{O}}_{\delta }$ prepared by focused ion beam induced deposition

We have prepared the new amorphous superconductor $\mathrm{M}{\mathrm{o}}_{\mathrm{x}}{\mathrm{C}}_{\mathrm{y}}\mathrm{G}{\mathrm{a}}_{\mathrm{z}}{\mathrm{O}}_{\delta }$ with a maximum critical temperature $T_c$ of 3.8,K by the direct-write nano-patterning technique of focused (gallium) ion beam induced deposition (FIBID) using $\mathrm{M}\mathrm{o}(\mathrm{C}\mathrm{O}{)}_6$ as precursor gas. From a detailed analysis of the temperature-dependent resistivity and the upper critical field we found clear evidence for proximity of the samples to a disorder-induced metal-insulator transition. We observed a strong dependence of $T_c$ on the deposition parameters and identified clear correlations between $T_c$, the localization tendency visible in the resistance data and the sample composition. By an in-situ feedback-controlled optimization process in the FIB-induced growth we were able to identify the beam parameters which lead to samples with the largest $T_c$-value and sharpest transition into the superconducting state.