Spin-size disorder model for granular superconductors with charging effects

Enzo Granato; Giancarlo Jug

doi:10.1016/j.physb.2009.07.034

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arXiv · 0907.3120

Spin-size disorder model for granular superconductors with charging effects

Enzo Granato·Giancarlo Jug

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Abstract

A quantum pseudo-spin model with random spin sizes is introduced to study the effects of charging-energy disorder on the superconducting transition in granular superconducting materials. Charging-energy effects result from the small electrical capacitance of the grains when the Coulomb charging energy is comparable to the Josephson coupling energy. In the pseudo-spin model, randomness in the spin size is argued to arise from the inhomogeneous grain-size distribution. For a particular bimodal spin-size distribution, the model describes percolating granular superconductors. A mean-field theory is developed to obtain the phase diagram as a function of temperature, average charging energy and disorder.

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Enzo Granato, Giancarlo Jug. 2009-07-17. Spin-size disorder model for granular superconductors with charging effects. https://doi.org/10.1016/j.physb.2009.07.034

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