Materials grown and studied include superconductors, high index dielectrics, magnetic films, and metallic coatings.
The latter can be improved at the expense of bandwidth by using superconductors.
But if you add charge carriers by chemically doping them they become superconductors with transition temperatures of up to 135K.
The first is a study of the temperature dependences of magnetotransport quantities in the normal state of the cuprate high-temperature superconductors.
Wonder if anyone's tried replicating the thing using ceramic superconductors and then cooling the thing off with liquid nitrogen to see what happens.