Electronic structure ofCeAg2Ge2studied by resonant photoemission spectroscopy

Abstract

The electronic structure of CeAg 2 Ge 2 single crystal has been investigated by using valence-band photoemission at different photon energies ranging from 110 to 150 eV. Resonant photoemission has been observed near the 4d threshold of Ce at 121 eV. The constant initial-state spectra shows two photoemission features having 4f character near the Fermi level at −0.4 and −1.7 eV which exhibits Fano-type sharp resonance character. The experimental spectra have been interpreted with the help of calculations based on full-potential linearized augmented plane-wave method using density-functional theory. Excellent agreement has been obtained between the theory and the experiment. The origin of the feature near to Fermi level is related to the Ce 4f states and the feature at −1.7 eV is related to the strong hybridization between the Ce 4f and 5d, Ag 4d and Ge 4p states.Resonant photoemission spectroscopy ͑RPES͒ has emerged as a very powerful tool to understand the electronic states of rare earths. From last few decades, Ce-based intermetallic compounds have attracted much attention for their various ground-state properties, such as the magnetism, nonmagnetic heavy Fermion, and quantum criticality, etc. 1-6 The diverse ground states are due to the competition between the Ruderman-Kittel-Kasuya-Yosida interaction and the Kondo effect. 7 CeAg 2 Ge 2 belongs to a wide class of cerium compounds that crystallize in the ThCr 2 Si 2 structure having a body-centered tetragonal lattice. 6 At room temperature it exhibits a paramagnetic phase while at low temperature an antiferromagnetic phase with T N = 7 K is reported. 5,6 More recently, detailed studies were performed on a single crystal, which has shown that CeAg 2 Ge 2 orders antiferromagnetically at 4.6 K. 8 The neutron-diffraction experiment shows a sine modulated structure with a magnetic moment equal to 1.85 B at T = 1.5 K. 6 In the Ce based intermetallic alloys it is believed that the ground-state properties depend on the strength of hybridization of the f electrons with the delocalized band states and this motivated us to understand the electronic structure of CeAg 2 Ge 2 . In the present work, we investigate the occupied electronic states of CeAg 2 Ge 2 at room temperature and try to provide a clear understanding of the hybridization between the local Ce 4f electrons and the itinerant conduction electrons by the systematic Ce 4d-4f RPES study.CeAg 2 Ge 2 single crystal was grown by the self-flux method. 8 For the PE measurements the sample has been mechanically polished to mirror finish using quarter micron diamond paste. The RPES measurements on this sample were carried out at the angle-integrated PE beamline on the Indus-1 synchrotron radiation source. 9 The valence-band ͑VB͒ photoemission spectra were recorded using a photon energy of 110-130 eV in very small steps of 1 eV. The energy analyzer from Omicron ͑EA125͒ is used to measure the spectra at room temperature. The spectra were normalized by the photon flux estimated from the photocurrent from the post mirror of th...

Large positive magnetoresistance and Dzyaloshinskii–Moriya interaction in CrSi driven by Cr 3d localization

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“… 49 . The PDOSs have been broadened by using the standard procedure reported elsewhere 1 , 26 . The features obtained in the valence band at RT shows a very good agreement with the reported theoretical calculation 49 .…”

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Electronic structure of buried Co-Cu interface studied with photoemission spectroscopy

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Ce 4f electronic states of CeO1−xFxBiS2 studied by sof

“…Off-and on-resonance spectra (thin and thick curves, respectively) are measured at two photon energies 870 eV (A) and 881.7 eV (B) in x-ray absorption spectra near the Ce M 5 edge shown in the inset, respectively. Each spectrum is magnified by the scale factor denoted on the right side of the figure. is due to the Fano profiles and, therefore, can be interpreted as "antiresonance phenomena" [39,40]. The major intensity distributions indicate the partial density of states (pDOS) of O 2p and S 3p multiplied photoemission cross sections.…”