Inductive Critical Currents in Mo/Nb layered structures

We have carried out measurements of inductive critical currents in Mo/Nb layered films. The films were grown by magnetron sputtering onto silicon substrates from separate sources. We grew films with the structure (N/S)$^{m}$, where the Mo/Nb bilayer is repeated $m$ times. Here the base bilayer unit is composed of a Mo layer 36.9 nm thick and a Nb layer 43.2 nm thick, while $m$ varies from 1 to 4. The films grow with (110) orientation, as expected for bcc materials. Inductive critical currents were measured using a third harmonic technique, while superconducting transition temperatures ($T_{c}$) were measured both resistively and inductively. The films were cooled by a cryocooler down to temperatures of approximately 6 K. We find the $T_{c}$ and the critical current density ($J_{c}$) are nearly independent of $m$. $J_{c}$ varies as $(1-t)^{3/2}$ as expected from Ginzburg-Landau theory (here $t$ is the reduced temperature, $T/T_{c}$). Measurements of $J_{c}$ have also been made in low magnetic fields, and will be discussed.