A MECHANISM TO STABILIZE THE NONUNITARY STATE FOR THE HEAVY-FERMION SUPERCONDUCTOR UPT3

We consider a mechanism to stabilize the non-unitary state proposed fo r the pairing state of the heavy Fermion superconductor UPt3. If the d erivative of the density of states with respect to the energy is finit e at the Fermi surface, the non-unitary superconducting state has a ma gnetic moment. The mechanism we consider is concerned with this proper ty and similar to Stoner's theory for ferromagnetism. We find, by cons tructing the GL free energy, that the following two conditions are cru cial: i) the electron-hole asymmetry of the density of states is rathe r large; ii) the system is in a nearly ferromagnetic state.