A two-component spin system with cubic anisotropy sufficiently large to remove the renormalization-group fixed point is investigated using differential recursion relations. An explicit free energy is constructed and it is verified explicitly that the loss of a fixed point corresponds to a first-order transition to the system's ordered state. A tricritical point is located and scaling properties of the first-order transition are investigated close to it.

• Received 28 April 1977

DOI:https://doi.org/10.1103/PhysRevB.18.1406