Crystal-field effects and disorder on the single-ion states of heavy fermions

In this study, we examine the crystal-field effects on the single-ion states for various heavy fermion elements and systems. Using Stevens parameters and exact diagonalization, we generate a first-order approximation of crystal-field disorder as systems undergo phase transitions between D₂, D₃, and D₄ symmetries. Furthermore, we examine the effect on transport properties, as determined from the state, and apply it to the known cerium and ytterbium systems.