Cooperativity in the adsorption of magnetic colloidal particles

In this paper we investigate the adsorption of magnetic particles onto magnetically patterned substrates. We find that the adsorption process is cooperative, where the probability of adsorption decreases with increasing substrate occupancy (namely, density of adsorbed particles). The effect of cooperativity can be accounted for by a simple modification of the adsorption probability as manifested by the binomial distribution. The negative cooperativity found in the magnetic particle adsorption is not due to direct repulsion between particles, but to screening of the surface's magnetic field by previously adsorbed particles. Thus, the adsorption of magnetic colloids on magnetic substrates is a self-limiting process.

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