Photoemission study of (PbEuGd)Te layers under Gd or Te atoms treatment

Abstract

Substitution of Gd 3+ for Eu 2+ ions in EuTe leads to the introduction of Gd 5d electrons to the conduction band and antiferromagnetic order of EuTe (Heisenberg magnetic semiconductor) can be replaced by ferromagnetic state due to RKKY interaction. The layers were grown by MBE method on BaF 2 (1 1 1) substrate. Layer of Te deposited on top of (EuGd)Te protects surface of oxidation. Heating in 320• C leads to Te atoms desorption and to improvement of the layer electronic structure. Additional Gd atoms were sequentially deposited on the layer of (PbGd)Te and set of Fano resonance curves were observed for ions of Gd. The Fano type photoemission resonance corresponding to the 4d-4f transitions were studied for Eu and Gd.

Electronic structure of epitaxial SrRuO3 films studied by resonant photoemission

“…3 the Fano resonance curves for peaks A and B originating from the Ru 4d orbitals are presented. Although this resonance effect was found rather broad and subtle, compared with well-known 2p-3d and 4d-4f cases (Sato et al, 1998;Orlowski et al, 2007), the Fanotype profile of A and B spectra clearly shows the enhancement of 4d shell related to VB spectral features. The shape of Fano resonance can be expressed as…”

Resonant Photoemission Study οf 4f Electrons on the Surface οf Semiconductors

“…The Eu 2+ peaks became sharp and narrow and the Eu 3+ /Eu 2+ concentration ratio became negligible small. Furthermore, the Te 4d peak became also narrow and its spin-orbit splitting became more distinctly visible [21,24]. In this way the proper conditions for annealing of the layer to obtain clean surface and crystalline layer with proper stoichiometry were found.…”

“…The investigated samples of (EuGd)Te were grown in home-built MBE machine using effusion cells for Eu, Gd and Te sources in the Institute of Physics, Polish Academy of Sciences in Warsaw [21][22][23][24]. The layers were grown on the freshly cleaved in air BaF 2 (cubic structure with lattice constant a 0 = 6.20Å) (111) surface.…”

“…doped crystal or organic compounds). The anomaly strong Fano-type resonance [8][9][10] correlated to the highly localized transitions 3p 6 −3d n or 4d 10 −4f n in transition metal [10][11][12][13][14][15][16][17][18][19][20] or rare-earth [20][21][22][23][24][25][26][27][28][29][30][31][32] atoms, respectively, were observed and applied for study of electronic structure and contribution of the states of these atoms to the semimagnetic or magnetic semiconductors valence band electronic structure. Continuous, high intensity and tunable light source gives the possibility to study particular resonance transition effects appearing for single isolated atoms as well as for atoms incorporated in the clusters, liquids, volume of the solids or their surface.…”