Quantum phase transitions in disordered dimerized quantum spin models and the Harris criterion
2010 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 17, 172409- p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2010. Vol. 82, no 17, 172409- p.
heisenberg-antiferromagnet, quenched disorder, critical-behavior, mott-insulator, ground-state, systems, chains
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:kth:diva-27356DOI: 10.1103/PhysRevB.82.172409ISI: 000284397500001ScopusID: 2-s2.0-78649661105OAI: oai:DiVA.org:kth-27356DiVA: diva2:377572
QC 201012142010-12-142010-12-132010-12-14Bibliographically approved