I think it's mostly eliminating random thermal motions that would otherwise swamp out the faint effects you're trying to measure, in this case such thermal effects would probably jiggle the cobalt atoms so much that they wouldn't line up properly.

Go low enough however and you do get strange quantum effect-related formation of Bose-Einstein condensates, and its even stranger newly discovered cousin, the Rydberg polaron:

https://en.wikipedia.org/wiki/Rydberg_polaron