Rare earth 4f states in A(1-x)(IV)RE(x)B(VI) diluted magnetic semiconductors

Resonant photoemission spectroscopy has been applied to study the group of Pb1-xRExBVI (RE=Eu, Gd; B=Te, Se, S) diluted magnetic semiconductors. Energ y distribution curves, as well as constant-initial-state or constant-final- state photoemission spectra have been taken for photon energies near to the intra-ion Eu 4d-->4f or Gd 4d-->4f transitions. The Eu 4f and Gd 4f contri butions to the electronic structures of the crystals have been determined b y comparison of photoemission spectra taken on and off resonance. The local ized character of the Eu(Gd) 4f(7) shell has been confirmed by the analysis of the shape of the corresponding spectral feature. The influence of the h ost crystal ionicity on the position of the RE 4f shells with respect to th e valence band is discussed. (C) 1999 Elsevier Science S.A. All rights rese rved.