Two‐ion anisotropic interaction from band f electron hybridization and magnetic ordering in uranium intermetallics

We have generalized the Coqblin‐Schrieffer type two‐ion anisotropic interaction to f2 and f3 configurations (U4+ and U3+). This interaction between ions occurs via the hybridization with the intervening sea of band electrons (i.e., via resonant mixing at each site with f component of band electrons when expressed in spherical waves about that site). With the addition of small antiferromagnetic Heisenberg (isotropic Ruderman‐Kittel) interaction and crystal‐field interaction, we obtain a 2k noncollinear ground state with a type I collinear antiferromagnetic state at slightly higher energy. It appears likely that this ordering of states will provide a transition with increasing temperature from a noncollinear 2k magnetic structure to a type I collinear structure as observed experimentally in UP and UAs.