Magnetism in one-dimensional disordered systems
A system of localized spins, randomly distributed on a one-dimensional array of sites and interacting via a nearest neighbor exchange which depends exponentially on the random spin separation, is studied. We have obtained the low temperature behavior of the magnetic susceptibility (χ ∫ T−Y) the heat capacity (C ∫ T−α) and the correlation length (ε ∫ T−ν), for the one-dimensional disordered Heisenberg and Ising models and for ferro and antiferromagnetic coupling. We found that in the Heisenberg case the exponents λ, α and ν change from nonuniversal to universal when the concentration of the spins reaches a critical value, while for the Ising model they are always concentration dependent. Experiments are suggested in order to observe the cross-over phenomena.
KeywordsHeat Capacity Correlation Length Ising Model Antiferromagnetic Coupling Neighbor Exchange
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