Oh wait, you're right. I misread the title. Don't we already have room temperature semiconductors?

Yep. This has interesting magnetic properties.

In magnetic materials, you must calculate separately the current with spin up and spin down and there ara meny interesting applications. My favorite is[1] https://en.wikipedia.org/wiki/Giant_magnetoresistance

[1] Was. Because it has used for hard disks (see the applications section). Now SSD ruins the interesting anecdote.

Oh wow, I had the same misread and the same gut reaction.