Superconductors exhibit a large positive dR/dT on the superconducting phase transition.
Normal (non-superconducting) metals typically exhibit a positive dR/dT that decreases to zero at very low temperatures.
The decrease in Joule heating will cause the device to return to its equilibrium temperature.
Thus the Joule heating amplifies a change in temperature, an effect known as positive electrothermal feedback.
Electrothermal feedback is important for describing the performance of several types of photodetectors such as the bolometer, the transition edge sensor,[1] and the superconducting nanowire single-photon detector.