Nature of the spin-glass phase in dense packings of Ising dipoles with random anisotropy axes

J. J. Alonso; B. Alles

doi:10.1088/1361-648x/aa7a1a

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arXiv · 1610.09131

Nature of the spin-glass phase in dense packings of Ising dipoles with random anisotropy axes

J. J. Alonso·B. Alles

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Abstract

Using tempered Monte Carlo simulations, we study the the spin-glass phase of dense packings of Ising dipoles pointing along random axes. We consider systems of L^3 dipoles (a) placed on the sites of a simple cubic lattice with lattice constant $d$, (b) placed at the center of randomly closed packed spheres of diameter d that occupy a 64% of the volume. For both cases we find an equilibrium spin-glass phase below a temperature T_sg. We compute the spin-glass overlap parameter q and their associated correlation length xi_L. From the variation of xi_L with T and L we determine T_sg for both systems. In the spin-glass phase, we find (a) decreases algebraically with L, and (b) xi_L/L does not diverge as L increases. At very low temperatures we find comb-like distributions of q that are sample-dependent. We find that the fraction of samples with cross-overlap spikes higher than a certain value as well as the average width of the spikes are size independent quantities. All these results are consistent with a quasi-long-range order in the spin-glass phase, as found previously for very diluted dipolar systems.

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J. J. Alonso, B. Alles. 2016-10-28. Nature of the spin-glass phase in dense packings of Ising dipoles with random anisotropy axes. https://doi.org/10.1088/1361-648x%2Faa7a1a

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