Quantum Criticality and the Alpha/Delta Puzzle
  In this paper we suggest a novel explanation for the alpha-delta transition in plutonium based on an analogy between the evolution of the actinide ground state as a function of spin orbit coupling and the behaviour of thin film superconductors in a magnetic field. The key point is that in metals with a low carrier density spin-orbit interactions give rise to low energy monopole-like solitons with quantized spin currents, which play much the same role as Abrikosov vortices in thin film superconductors. In alpha-plutonium these solitons form an ordered solid, while in impurity stabilized delta-plutonium they form a pair condensate. 
George Chapline