Superconductive materials (cold) materials, act in such a way because there is no inherent blockage of path (electricity). It is comparable to a standing wave; or a series of atomic waves which are at such a state in which vibration rates are non-interferent. This allows for electrical interfacing; or better phased current paths (vibration). It is entirely based on transfer through wave (phase) states. In the natural world; more excitement leads to more vibration; and a longer overall path in which to follow. In some cases, no path (phase possibility) at all. Cold is a rectifier, in that is affects excitement states. The rectification is the alignment, or ease of path. Similar to turning a winding wave into a straight line.
Here is a video (wave) representation of what is happening. This is a brief visualization of what causes superconductivity. Think of lower frequency as the less excited electron state (cold). Note the waveform is a representation of a combination of atomic structures (group function). It is similar to building a wall out of moving bricks. It is going to be easier to find the appropriate path between all bricks if you were to slow down their movement. The size of the brick (structure of the atom) will affect how the path is found.
We should be able to use combinations of materials which are both superconductive at higher and lower temperatures in order to transfer with consistency the superconductive states; without the use of excessive coolant; an expulsive liquid membrane would be required (just like how heat is released through our bodies); as it would act as an insulator, and conductor itself, in which it would allow electron flow through all of the combined materials; or the electrons to find the most conductive path as each conductive state alternates. There should in time be a discover-able way to do so without the use of coolant at all, but strictly through the use of feedback circuits.
To add, superconductivity is the 0hz equivalent to conversion from AC, to DC current; where the current threshold has reached a point in which all current points are a positive value in relation to the currents ability to pass through. Here is additional proof of this: