Mathematical Proceedings of the Cambridge Philosophical Society

Research Article

On Ising's model of ferromagnetism

Mr R. Peierls

Ising discussed the following model of a ferromagnetic body: Assume N elementary magnets of moment μ to be arranged in a regular lattice; each of them is supposed to have only two possible orientations, which we call positive and negative. Assume further that there is an interaction energy U for each pair of neighbouring magnets of opposite direction. Further, there is an external magnetic field of magnitude H such as to produce an additional energy of − μH (+ μH) for each magnet with positive (negative) direction.

(Received May 16 1936)

(Accepted October 26 1936)