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Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta

Physics Faculty Research & Creative Works

We study the ferromagnetic phase transition in a randomly layered Heisenberg model. A recent strong-disorder renormalization group approach [Phys. Rev. B 81, 144407 (2010)] predicted that the critical point in this system is of exotic infinite-randomness type and is accompanied by strong power-law Griffiths singularities. Here, we report results of Monte-Carlo simulations that provide numerical evidence in support of these predictions. 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. In addition, we calculate the time autocorrelation function of the spins. It features a very slow …