There was a pretty solid basis for believing that 2-dimensional crystals were thermodynamically unstable and thus couldn’t exist. Then in 2004 Geim and Novoselov did it (isolated graphene for the first time) and people had to re-scrutinize the theory, since it was obviously wrong somehow. It turns out that the previous theory was correct for 2D crystals of essentially infinite size, but it seems to not apply for non-infinite crystals. At least that is how it was explained to me once by a theorist on the subject.
There was a pretty solid basis for believing that 2-dimensional crystals were thermodynamically unstable and thus couldn’t exist. Then in 2004 Geim and Novoselov did it (isolated graphene for the first time) and people had to re-scrutinize the theory, since it was obviously wrong somehow. It turns out that the previous theory was correct for 2D crystals of essentially infinite size, but it seems to not apply for non-infinite crystals. At least that is how it was explained to me once by a theorist on the subject.
The opening paragraph of this paper cites the relevant literature: http://cdn.intechopen.com/pdfs/40438/InTech-The_cherenkov_effect_in_graphene_like_structures.pdf