For an electromagnet to effectively levitate a permanent magnet underneath it without external support structures, the electromagnet must be oscillating within a delicate range. I've heard that superconductors exhibit a magnetic field because they have such little electrical resistance that an electric current can flow around almost indefinitely. But one time I saw this video of a high-temp electromagnet (cooled with LN2) in a watch glass on a ring stand, about the size of an Oreo (but twice as thick), and below it, under the watch glass, a nickel- or dime-sized permanent magnet was levitating. So, since superconductors are basically just another electromagnet, why don't they need to oscillate in order to levitate a permanent magnet below them? Is there something else about the superconductors that makes them special? @SolomonSlow mentioned something called 'the Meissner' effect? I honestly don't know. I tried to find an answer online, but couldn't find anything. Any help is greatly appreciated.
Note: I will do my best to find the original video, and post it here when I do.