Abstract
We use quantum Monte Carlo simulations to study effects of disorder on the quantum phase transition occurring versus the ratio g = J/J' in square-lattice dimerized S = 1/2 Heisenberg antiferromagnets with intradimer and interdimer couplings J and J'. The dimers are either randomly distributed (as in the classical dimer model), or come in parallel pairs with horizontal or vertical orientation. In both cases the transition violates the Harris criterion, according to which the correlation-length exponent should satisfy v >= 1. We do not detect any deviations from the three-dimensional O(3) universality class obtaining in the absence of disorder (where v approximate to 0.71). We discuss special circumstances which allow v < 1 for the type of disorder considered here.
Published in:
Physical Review B 82,17 (2010)
Link to original published article:
http://dx.doi.org/10.1103/PhysRevB.82.172409
Date of Version
November 2010
Recommended Citation
Yao, D. X.; Gustafsson, J.; Carlson, E. W.; and Sandvik, A. W., "Quantum phase transitions in disordered dimerized quantum spin models and the Harris
criterion" (2010). Department of Physics and Astronomy Faculty Publications. Paper 1352.
https://docs.lib.purdue.edu/physics_articles/1352