Electronic structure of RCo_xGe₂ (R=Ce, Pr, Gd) compounds

Abstract

The electronic structure of the RCo x Ge 2 (R=Ce, Pr, Gd) compounds with the orthorhombic crystal structure of CeNiSi 2 -type was studied by X-ray photoemission spectroscopy. The valence bands of CeCo 0.86 Ge 2 and PrCo 0.85 Ge 2 compounds have the similar character. Near the Fermi level the broad peak corresponding to the Co 3d and R 4f and 5d6s states is observed. In the case of GdCo 0.64 Ge 2 , the strong intensity peak at 8.7 eV corresponding to Gd 4f states is observed. The analysis of the XPS spectra of Ce and Pr 3d 5/2 and 3d 3/2 in the Gunnarson-Schönhammer model give the information on the hybridization of the f orbital with the conduction band. The hybridization energy equal 93 eV for R=Ce and 143 eV for R=Pr, respectively indicate stability of the shell in these compounds.

Magnetic and electronic properties of RCoxGe2 (R=Pr, Nd) compounds

“…The determined values of the hybridization energy are similar to that found for the isostructural compound CeCo 0.89 Ge 2 , which does not order magnetically down to 1.5 K [8].…”

“…These investigations are a part of our extended project aiming at determination of magnetic and electronic structures of the 1:1:2 rare earth intermetallics. This paper completes the series of papers [6][7][8] that report the results obtained for the RCo x Ge 2 compounds.…”

Magnetic, electric and thermoelectric properties of ternary intermetallics from the Ce–Co–Ge system

“…The value of the effective magnetic moment in Ce 3 CoGe 2 is close to the theoretical one calculated for a free Ce 3þ ion (2.54 m B ). In Ce 2 CoGe 3 and CeCo 0.86 Ge 2 m eff is slightly larger than expected, possibly due to a noticable 3d-electron contribution of Co [19]. The large and negative values of q p are characteristic of cerium-based intermetallics that exhibit strong magnetocrystalline anisotropy, antiferromagnetic correlations or Kondo interactions.…”