Phase boundaries near critical end points. II. General spherical models

Abstract

We study d-dimensional ferromagnetic spherical models with power-law, J(R)-1/R d+u (u < 2), or short-range (u ~2) interactions and on-site terms of the form Ds2-l Uls 4+ Vs 6, and establish that the phase diagrams for ali d and u with u < d < 2u, may exhibit critica/ end points terminating nonclassical criticai lines; tricritical points may arise only for -}u ~ d. The phase boundary D u ( T, h), where h is the magnetic field, between the noncritical, spectator phase and the ordering and criticai phase is shown to exhibit singularities at the end point with amplitudes obeying the universal ratio laws advanced on phenomenological grounds in Part I.