Level spectroscopy of the square-lattice three-state Potts model with a ferromagnetic next-nearest-neighbor coupling.
We study the square-lattice three-state Potts model with the ferromagnetic next-nearest-neighbor coupling at finite temperature. Using the level-spectroscopy method, we numerically analyze the excitation spectrum of the transfer matrices and precisely determine the global phase diagram. Then we find that, contrary to a previous result based on the finite-size scaling, the massless region continues up to the decoupling point with Z3 x Z3 criticality in the antiferromagnetic region. We also check the universal relations among excitation levels to provide the reliability of our result.
Otsuka
Hiromi
H
Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 Japan.
Mori
Koutaro
K
Okabe
Yutaka
Y
Nomura
Kiyohide
K