(a) Use the partition function to find an exact expression for the magnetization M and the susceptibility X = dM/dB as a function of temperature and magnetic field for the model system of magnetic nm tanh(mB/τ), as derived in (46) by another method. Here n is the particle concentration. The result is plotted in figure.

(b) Find the free energy and express the result as a function only of τ and the parameter x ≡ M/nm

(c) Show that the susceptibility is X = nm²/τ in the limit mB << τ,

Transcribed Image Text:

1.0 %3- 0.5 1.5 2.0 0.5 n:B