is superconducting electronics dying?

used to be a very hot topic i heard.. not sure why the efforts on it are winding down?

For the high temperature superconducting, what are the high temperature range so it can be called "high temperature"?

Everything above liquid helium temperature (4K), e.g. liquid nitrogene (77K).

It's too expensive to run the superconducting electronic devices as the have to be cooled to very low temperature. The high temperature refers to the superconductors discovered in the late 1980s. Typically with a transition temperature between 35K to 130K. The previous highest transition temperature was 23.5K obtained on Nb3Ge.

Thank you for the reply. What is transition temperature? So "high" temperature superconducting is still pretty low temperature actually.

Superconductors are only superconducting below a certain temperature -> transition temperature.

Transition temperature is the temperature that a superconductor changes from normal state to superconducting state. The "high" temperature superconductor is in comparison to the conventional superconductor, which is referred as "Low" temperature superconductor. There is another term "Room" temperature superconductor, which the scientists are dreaming to discover, but has so far never been found.

Thank you Phytech & volker_muehlhaus for the great and very straightforward answers!

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Why do strange materials such as "Nb3Ge" have to be used? Are they really good conductors? I guess the regular metal materials we see cannot do the job probably.

It might be surprising, but superconducting materials do not need to be good conductors at room temperature. I worked with the popular Yttrium barium copper oxide high temperature superconductor, which is actually a pretty bad conductor at room temperature.

That is very interesting: at low temperature, bad conductors become good conductors.

How about those conventional good conductors (coppers, silver etc.) at room temperatures, do they turn into bad conductors at low temperature?

Sorry for the silly questions. I am a layman to superconductor. Just need to know a few ABC about it.

No. The resistivity of any pure metal is a monotonous function of temperature. Similar to superconductors, it is dropping considerably at a certain low temperature (a few 10 K), but not to zero. Finally, many metals are showing superconductance below 0.01K.