Abstract
Unbinding transitions of amphiphilic membranes are studied by a renormalization group (RG) approach. Both for fluid and for crystalline membranes, a whole line of RG fixed points is found. Each line consists of two branches: one branch describes complete unbinding, the other branch represents continuous unbinding transitions. The critical behaviour at the unbinding transition exhibits three scaling regimes A), B), an d C). Regime A) is characterized by essential singularities, and regime B) by parameter-dependent critical exponents. In regime C), a discontinuous transition with rather unusual scaling properties is expected by analogy with wetting transitions.