We study the effects of dissipation on a randomly diluted transverse-field Ising magnet close to the percolation threshold. For weak transverse fields, a percolation quantum phase transition separates a superparamagnetic cluster phase from an inhomogeneously ordered ferromagnetic phase. The properties of this transition are dominated by large frozen and slowly fluctuating percolation clusters. This leads to a discontinuous magnetization-field curve and exotic hysteresis phenomena as well as highly singular behavior of magnetic susceptibility and specific heat. We compare our results to the smeared transition in generic dissipative random quantum Ising magnets. We also discuss the relation to metallic quantum magnets and other experimental realizations.
J. A. Hoyos and T. Vojta, "Percolation Transition and Dissipation in Quantum Ising Magnets," Physical Review B - Condensed Matter and Materials Physics, American Physical Society (APS), Jan 2006.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevB.74.140401
Keywords and Phrases
Magnetic Hysteresis; Superparamagnetism; Diluted magnetic semiconductors; Ferromagnetism; Hysteresis; Ising model; Magnetic susceptibility; Paramagnetism; Percolation (Statistical physics); Phase transformations (Statistical physics); Specific heat
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