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Phase Transitions of Ising Model

Zero Field. Curie Point

Let H=0 (symmetric case). Entropy wants spins to be disoriented, energy--to be parallel


Non-Zero Field. Susceptibility

If $H\ne0$, magnetization M is parallel to H. There is a function M(H,T). What happens at $H\to0$?

In critical point susceptibility is infinity!

Since amplitude of fluctuations is

\left\langle (\Delta M)^2\right\rangle = \frac{\chi kT}{V}\end{displaymath}

the fluctuations infinitely grow at Tc!

Phase Diagram

 \psfrag{Fi... transitions}{First order phase transitions}

© 1997 Boris Veytsman and Michael Kotelyanskii
Mon Oct 13 22:07:20 EDT 1997