= First-order transition in a cubic-quartic Landau potential
{title2=$A_2=2A_3^2/(9A_4),\quad\Delta m=-2A_3/(3A_4)$}
For a real unrestricted scalar <order parameter> and $A=A_2m^2/2+A_3m^3/3+A_4m^4/4$ with $A_3\ne0$ and $A_4>0$, the disordered <global minimum> is replaced discontinuously by a nonzero minimum at the displayed <phase coexistence> condition. At coexistence $A=A_4m^2[m+2A_3/(3A_4)]^2/4$. Ordered <stationary points> first appear at the <spinodal point> $A_2=A_3^2/(4A_4)$, while the disordered point loses local stability at $A_2=0$; neither local limit is the equilibrium transition condition.
Back to article page
