Mean Field Phase Transition

Landau theory: F(m) = a(T−Tc)m² + bm⁴ − Hm · Order parameter & symmetry breaking

Temperature T/Tc: 1.10

Field H: 0.00

Transition type:

—

m* (order param)

—

F(m*)

—

χ = dm*/dH

—

d²F/dm² at m*

Second order: order parameter m grows continuously below Tc as m ~ (Tc−T)^β (β=1/2 mean field). First order: m jumps discontinuously. External field H breaks symmetry and shifts transition. Susceptibility χ diverges at Tc.