Pinning behavior of Nb3Ge thin film superconductors

Nb
3
Ge thin film superconductors have been prepared by coevaporation and cosputtering on hot sapphire substrates. Films were analyzed by X-ray and backscattering techniques. Critical current density, j
c
, has been determined between 4.2 K and T
c
in magnetic fields up to 13 Tesla, upper critical field, B
c2
was obtained from resistive transition or by extrapolation from j
c
. Pinning in coevaporated films obeys temperature scaling, whereas cosputtered films have their pinning maximum at a constant field value, B
p
. A correlation between B
p
and the Nb
3
Ge film microstructure is suggested as pinning increases with B
p
.