Superparamagnetism in the 1D Ising model
The temperature dependence of the order parameter (〈M2〉, the mean-square spin excess per spin) for a system with a finite number of spins of the 1D Ising model was investigated. It was shown that there is a nonzero temperature Ts below which 〈M2〉 rapidly tends to unity. The analogy between the 1D ensemble of a finite number of spins and a system of superparamagnetic particles is discussed.