Physical review. B, Condensed matter
First- and second-order phase transitions in a system with multispin interactions
Amos Maritan, Attilio L. Stella, Carlo Vanderzande
Abstract
A quantum model with $n$-spin interactions is studied in the ground state. When $n\ensuremath{\rightarrow}\ensuremath{\infty}$ the model is solved exactly by mean-field theory and undergoes a first-order transition. The transition is expected to become second order for $n<{n}_{c}$. With exploitation of self-duality and suitably improved mean-field approximations, a recently proposed criterion leads to the conjecture ${n}_{c}=3$ in one dimension. For the two-dimensional case the transition appears to be definitely of first order for $n=3 (2<{n}_{c}<3)$.