Collège Doctoral - Doktorandenkollegien

Statistical Physics of Complex Systems

Coventry - Leipzig - Lviv - Nancy

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Seminar

Evidence of Unconventional Universality Class in a Two-Dimensional Dimerized Quantum Heisenberg Model
Sandro Wenzel
ITP Leipzig
le Thursday 22 May 2008 à 10h00
Salle de séminaire du groupe de Physique Statistique
The two-dimensional J-J' dimerized quantum Heisenberg model is studied on the square lattice by means of (stochastic series expansion) quantum Monte Carlo simulations as a function of the coupling ratio alpha=J'/J. The critical point of the order-disorder quantum phase transition in the J-J' model is determined as alpha=2.5196(2) by finite-size scaling for up to N=96x96 quantum spins. By comparing six dimerized models we show, contrary to the current believe, that the critical exponents of the J-J' model are not in agreement with the three-dimensional classical Heisenberg universality class which gives support to the notion of non-trivial critical excitations at the quantum critical point.


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