Breaking through the Mermin-Wagner limit in 2D van der Waals magnets

Abstract

The recent discovery of magnetism in van der Waals materials down to the monolayer seemed to challenge a long-established theoretical result, the Mermin-Wagner theorem, which states that long-range magnetic order does not exist in two dimensions with short-range interactions. Here, using state of the art computational methods, the authors show that for sample sizes usually used in experiments, the exchange interactions at the finite size is enough to stabilize magnetic order without any magnetic anisotropy.