Three-dimensional ferromagnetic CP(N-1) models

Understand

We investigate the critical behavior of three-dimensional ferromagnetic CP(N-1) models, which are characterized by a global U(N) and a local U(1) symmetry.

• We perform numerical simulations of a lattice model for N=2, 3, and 4.
• For N=2 we find a critical transition in the Heisenberg O(3) universality class, while for N=3 and 4 the system undergoes a first-order transition.
• For N=3 the transition is very weak and a clear signature of its discontinuous nature is only observed for sizes L>50.