Properties of a random bond Ising chain in a magnetic field

The Ising chain with random bonds in a magnetic field H=-Σi^Jᵢσᵢσᵢ₊₁-hΣi^σᵢ, where Jᵢ=±1 at random, and Σi^Jᵢ=0, represents a model of a magnetic glass, or of heteropolymer melting. Calculations of the thermodynamic properties of the chain as a function of field strength and temperature have been performed by Monte Carlo techniques. These results are compared with perturbation calculations for small and large values of h/T. The Monte Carlo results show, in agreement with the perturbation calculations, that the field-induced magnetization is generally smaller for the random bond model than for a chain of noninteracting spins. As T→0 the magnetization approaches the result for noninteracting spins.