Order—Disorder Phenomena. II. Elastic Constants of a Two‐Dimensional Ising Model

摘要

The mechanical behavior of an Ising model in which the spins are located on the particles of a compressible lattice has been investigated. Analytical expressions are derived for the spin contribution to all three independent elastic constants of a square ferromagnetic system. It is found that the constant area temperature dependence ofc11(the compressional stiffness constant) is dominated by a term proportional to the configurational specific heat. In contrast, the angle shear constant (denoted byc44) has a spin contribution which is directly proportional to the Ising internal energy. The other shear constantC′ is a more complicated function of temperature, but it is similar toc44in that both constant‐area shear constants have an inflection point of infinite slope atTc.