Mermin-Wagner Theorem and its implications

Debnarayan Jana

University of Calcutta

In this article, we would like to discuss the implications of Mermin-Wagner theorem, a well known theorem used in condensed matter physics to rule out the possibility of spontaneous magnetisation at non-zero finite temperature in one and two dimension for some class of model Hamiltonian having continuous symmetry. This similiraity of the absence of spontaneous magnetization can be invoked in other branches of condensed matter physics. Finally, we will try to shed some light on the debate related to the stability of 2D graphene sheet and magnetism of 1d finite linear chain consisting of Co atoms in the context of this theorem.