Resonant photoemission in CeNi single crystals

Kashiwakura, T.; Suzuki, Shoji; Okane, Tetsuo; Satō, Shigeru; Kinoshita, Toyohiko; Kakizaki, Akito; Ishii, Takehiko; Isikawa, Y; Yamagami, Hiroshi; Hasegawa, Akira

doi:10.1103/physrevb.47.6885

Cited by 17 publications

(4 citation statements)

References 61 publications

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“…This does not change the experimental conditions, but can considerably enhance the contributions from specific atomic orbitals . For Ce-based compounds, 4d − 4f ( ν = h 122 eV) [27,28] 5 resonant photoemission spectra of UO 2 [24]. The intensity of f U 5 states located at around 1 eV significantly enhanced at the d U 5 absorption edge ( ν = h 108 eV).…”

Section: Resonant Photoemissionmentioning

confidence: 99%

Band structures of 4fand 5fmaterials studied by angle-resolved photoelectron spectroscopy

Fujimori

2016

J. Phys.: Condens. Matter

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Recent remarkable progress in angle-resolved photoelectron spectroscopy (ARPES) has enabled the direct observation of the band structures of 4f and 5f materials. In particular, ARPES with various light sources such as lasers (hν ~ 7 eV) or high-energy synchrotron radiations (hν >/~ 400 eV) has shed light on the bulk band structures of strongly correlated materials with energy scales of a few millielectronvolts to several electronvolts. The purpose of this paper is to summarize the behaviors of 4f and 5f band structures of various rare-earth and actinide materials observed by modern ARPES techniques, and understand how they can be described using various theoretical frameworks. For 4f-electron materials, ARPES studies of CeMIn5(M = Rh, Ir, and Co) and YbRh2Si2 with various incident photon energies are summarized. We demonstrate that their 4f electronic structures are essentially described within the framework of the periodic Anderson model, and that the band-structure calculation based on the local density approximation cannot explain their low-energy electronic structures. Meanwhile, electronic structures of 5f materials exhibit wide varieties ranging from itinerant to localized states. For itinerant U5f compounds such as UFeGa5, their electronic structures can be well-described by the band-structure calculation assuming that all U5f electrons are itinerant. In contrast, the band structures of localized U5f compounds such as UPd3 and UO2 are essentially explained by the localized model that treats U5f electrons as localized core states. In regards to heavy fermion U-based compounds such as the hidden-order compound URu2Si2, their electronic structures exhibit complex behaviors. Their overall band structures are generally well-explained by the band-structure calculation, whereas the states in the vicinity of EF show some deviations due to electron correlation effects. Furthermore, the electronic structures of URu2Si2 in the paramagnetic and hidden-order phases are summarized based on various ARPES studies. The present status of the field as well as possible future directions are also discussed.

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Section: Resonant Photoemissionmentioning

confidence: 99%

Band structures of 4fand 5fmaterials studied by angle-resolved photoelectron spectroscopy

Fujimori

2016

J. Phys.: Condens. Matter

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“…The empirical parameters ⌫ and q are related to the Coulomb potential and the dipole matrix elements. We have not calculated the Coulomb potential and the dipole matrix elements but the determined ⌫ and q values appear to be reasonable when compared to the values previously reported for other Ce based compounds such as CeNi and Ce-Co. 25,26 To understand the origin of the features in the experimental VB spectra we show the total density of states ͑DOS͒ along with the total Ce, Ag, and Ge DOS in Fig. 4͑a͒.…”

mentioning

confidence: 99%

Electronic structure ofCeAg2Ge2studied by resonant photoemission spectroscopy

et al. 2010

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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...

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“…The two-hole bound state does not show dispersion. This is proved experimentally [6,[25][26][27][28]. Thus, the two-hole bound state has often been treated as a quasi-atomic state with the electronic configuration of 3d 8 4s.…”

Section: P)mentioning

confidence: 88%

MVV super Coster–Kronig spectra of nickel near the excitation threshold

Songsiriritthigul¹,

Wongkokua²,

Nakajima³

et al. 2005

J. Phys.: Condens. Matter

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The MVV super Coster-Kronig (sCK) spectra of metallic Ni have been measured near the 3p excitation threshold by varying excitation photon energy. The results have been interpreted on the basis of the Cini-Sawatzky theory. The measured sCK band has composite structure with features at electron kinetic energy of 49.8, 56.3, 59.5, and 60.5 eV. If we interpret the band at 49.8 eV to be the split-off quasi-atomic band, we can estimate the effective intra-atomic Coulomb energy at a large value of 8 eV. The spectral shape of the MVV sCK band measured by excitation with vacuum ultraviolet light does not coincide with that obtained by the Mg Kα excitation or with that of the L 3 VV Coster-Kronig band. The shape of the MVV sCK spectrum changes as excitation energy changes. The excitation-energy range in which such spectral change occurs extends from the 3p threshold to 10 eV above it. As the kinetic energy for the MVV sCK band starts to overlap that of the two-hole-bound-state band, the MVV sCK band changes its shape considerably and the two spectra become inseparable. In this excitation-energy region, the spectator electron excited optically forms a virtual bound state with the two 3d holes. The location of the apparent two-hole-bound-state band shifts toward high binding energy on the 3p-3d resonance. This can be interpreted as a kind of final state interaction. The suggested intermediate and final states of the single-step transition are consistent with the constant-initial-state spectra and total photoyield spectrum. The roles of the screening by conduction electrons and the sd hybridization are emphasized.

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Resonant photoemission in CeNi single crystals

Cited by 17 publications

References 61 publications

Band structures of 4fand 5fmaterials studied by angle-resolved photoelectron spectroscopy

Band structures of 4fand 5fmaterials studied by angle-resolved photoelectron spectroscopy

Electronic structure ofCeAg2Ge2studied by resonant photoemission spectroscopy

MVV super Coster–Kronig spectra of nickel near the excitation threshold

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