PuS, PuSe, PuTe: Relativistic semiconductors

Abstract

The equations of state of PuS, PuSe and PuTe were calculated from self-consistent energy band calculations in a number of ways: (1) With 5f electrons treated as localized and Pu divalent. In this case insulators were obtained which would have non-magnetic J = 0 ground states, in agreement with experiment. However, the calculated lattice constants were far too large. (2) With 5f electrons treated as localized and Pu trivalent. Metals were obtained, and trivalent Pu systems are normally magnetic. In addition the calculated lattice constants were too large. (3) With 5f-electrons treated as itinerant but with spin-orbit coupling neglected. All three systems were found to be metallic and the Stoner criterion for ferromagnetism was easily satisfied although experimentally no moment has been observed in these systems. The calculated lattice parameters were also too small. (4) With 5f-electrons treated as itinerant and fully relativistically. In this case all three systems were found to be semiconductors with calculated lattice constants in agreement with experiment and band gaps of between 0.2–0.4 eV.