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arXiv · 1109.4172

Infinite-randomness criticality in a randomly layered Heisenberg magnet

Fawaz Hrahsheh·Hatem Barghathi·Thomas Vojta
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Abstract

We study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte-Carlo simulations. Our results provide numerical evidence for the infinite-randomness scenario recently predicted within a {strong-disorder renormalization group approach}. Specifically, we investigate the finite-size scaling behavior of the magnetic susceptibility which is characterized by a non-universal power-law divergence in the Griffiths phase. We also study the perpendicular and parallel spin-wave stiffnesses in the Griffiths phase. In agreement with the theoretical predictions, the parallel stiffness is nonzero for all temperatures $T<T_c$. In contrast, the perpendicular stiffness remains zero in part of the ordered phase, giving rise to anomalous elasticity. In addition, we calculate the in-plane correlation length which diverges already inside the disordered phase at a temperature significantly higher than $T_c$. The time autocorrelation function within model $A$ dynamics displays an ultraslow logarithmic decay at criticality and a nonuniversal power-law in the Griffiths phase.

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Fawaz Hrahsheh, Hatem Barghathi, Thomas Vojta. 2011-09-19. Infinite-randomness criticality in a randomly layered Heisenberg magnet. https://doi.org/10.1103/physrevb.84.184202

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