I read that most type-2 superconductors have one quantum of flux (2*pi*h-bar/e) per flux filament (fluxon), but that a few have a different value (were fullerenes one of them?). I mentioned this to an professor I am doing some research for, and he challenged what I read. Now, I can't find what I read earlier. I have searched all day, but I can find anything addressing this. Has anyone heard of this?