Quantum Physics Division
Faculty of PhysicsAdam Mickiewicz University

Quantum phase transitions in the J-J ' Heisenberg and XY spin-½ antiferromagnets on a square lattice: finite-size scaling analysis

P. Tomczak1,2 , J. Richter2

1 Department of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614, Poznań , Poland
2 Institut für Theoretische Physik, Otto-von-Guericke Universität, Magdeburg, POB 4120, 39016 Magdeburg, Germany

J. Phys.A: Math.Gen., 34, L461-L466 (2001)
DOI: 10.1088/0305-4470/34/33/104


We investigate the critical parameters of an order-disorder quantum phase transition in the spin-½ J-J ' Heisenberg and XY antiferromagnets on a square lattice. Based on the excitation gaps calculated by the exact diagonalization technique for systems up to 32 spins and finite-size scaling analysis we estimate the critical couplings and exponents of the correlation length for both models. Our analysis confirms the universal critical behaviour of these quantum phase transitions: they belong to 3D O(3) and 3D O(2) universality classes, respectively.


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