Question

In solid state.. Calculate the exchange energy in a one-dimensional Ferromagnetic and Anti-Ferromagnetic, using the Ising model. What is the important parameter to determine which of states is the ground state? Help me,,

Answer 1

It is a standard model of a phase transistion using the approximation of mean field theory, the free energy is minimized and we can easily calculate the magnetization. The isling model shows the essential concept of how the balance between energy and entropy leads to a phase transistion.The important parameter to determine is the ground state is the interaction between neighbouring spins tends to induce parallel alignment of the neighbours.so it should be favourable (negative) when the neighbours are both +1 or -1 .