Infinite Randomness and Quantum Griffiths Effects in a Classical System: The Randomly Layered Heisenberg Magnet
We investigate the phase transition in a three-dimensional classical Heisenberg magnet with planar defects, i.e., disorder perfectly correlated in two dimensions. By applying a strong-disorder renormalization group, we show that the critical point has exotic infinite-randomness character. It is accompanied by strong power-law Griffiths singularities. We compute various thermodynamic observables paying particular attention to finite-size effects relevant for an experimental verification of our theory. We also study the critical dynamics within a Langevin equation approach and find it extremely slow. At the critical point, the autocorrelation function decays only logarithmically with time while it follows a nonuniversal power law in the Griffiths phase.
P. Mohan et al., "Infinite Randomness and Quantum Griffiths Effects in a Classical System: The Randomly Layered Heisenberg Magnet," Physical review B: Condensed matter and materials physics, vol. 81, no. 14, American Physical Society (APS), Apr 2010.
The definitive version is available at https://doi.org/10.1103/PhysRevB.81.144407
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01 Apr 2010