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Ichiki, Katsuya; Mimura, Koji; Anzai, H.; Uozumi, Takayuki; Sato, Hitoshi; Utsumi, Yuki; Ueda, Shigenori; Mitsuda, Akihiro; Wada, Hirofumi; Taguchi, Y.; Shimada, Kenya; Namatame, H.; Takeuchi, Masaki

doi:10.1103/physrevb.96.045106

Cited by 10 publications

(10 citation statements)

References 33 publications

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“…Broad structures around 1140 and 1170 eV are attributed to plasmon statellites related to the Eu 2+ 3d photoemission process. Compared to the Eu 3d spectrum of other divalent Eu compounds, such as EuRh 2 Si 2 (mean-Eu valence v ∼ 2.1 at 300-20 K) 29 and EuNi 2 (Si 0.21 Ge 0.79 ) 2 (v ∼ 2.2 at 300 K) 30 , the relative intensity of Eu 3+ components to those of Eu 2+ is small and buried in the tail of the Eu 2+ components and its statellite structures. As expected from magnetic susceptibility and Mössbauer measurements, the Eu valence states in the EuT Ge 3 series are very close to Eu 2+ .…”

Section: Resultsmentioning

confidence: 92%

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

et al. 2018

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Non-centrosymmetric EuT Ge3 (T =Co, Ni, Rh, and Ir) possesses magnetic Eu 2+ ions and antiferromagnetic ordering appears at low temperatures. Transition metal substitution leads to changes of the unit cell volume and of the magnetic ordering. However, the magnetic ordering temperature does not scale with the volume change and the Eu valence is expected to remain divalent. Here we study the bulk electronic structure of non-centrosymmetric EuT Ge3 (T =Co, Ni, Rh, and Ir) by hard x-ray photoelectron spectroscopy. The Eu 3d core level spectrum confirms the robust Eu 2+ valence state against the transition metal substitution with a small contribution from Eu 3+ . The estimated Eu mean-valence is around 2.1 in these compounds as confirmed by multiplet calculations. In contrast, the Ge 2p spectrum shifts to higher binding energy upon changing the transition metal from 3d to 4d to 5d elements, hinting of a change in the Ge-T bonding strength. The valence bands of the different compounds are found to be well reproduced by ab initio band structure calculations.

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Section: Resultsmentioning

confidence: 92%

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

et al. 2018

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“…The range of Eu-based compounds undergoes sharp valence transitions. In these compounds the Eu valence change dramatically in comparison with the most Ce-and Yb-based compounds in the same temperature region [74,75]. Usually, the FOVT transition is observed in such systems [76,77].…”

Section: Discussion Of the Resultsmentioning

confidence: 95%

Pressure influence on the valence and magnetic state of Yb ions in noncentrosymmetric heavy-fermion YbNiC2

et al. 2021

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We present studies of neutron diffraction, electrical resistivity, magnetic susceptibility, magnetization, and specific heat of noncentrosymmetric YbNiC 2 . At normal pressure, YbNiC 2 is a moderate heavy-fermion compound with Kondo lattice. At 16 K we observe an anomaly in the temperature dependence of specific heat which is ascribed to an abrupt valence change of Yb ions. At pressures above 7 GPa, the valence change and the Kondo lattice state are suppressed, and near a temperature of 10 K we detect the appearance of magnetic order. Above 5 GPa, the temperature dependence of the resistivity behaves similarly to other compounds of the CeNiC 2 -type family, indicating the formation of charge density waves. This is attributed to the nesting properties of the Fermi surface (FS) found within the density functional theory + dynamical mean field theory treatment. Our ab initio calculations also show that the valence of Yb in YbNiC 2 at normal conditions is 2.85, which increases with temperature and pressure. The FS of YbNiC 2 is anisotropic in shape in comparison with the 3D surface of YbCoC 2 .

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“…Recently, it has been reported that the spectral shape of Eu 3+ 3d multiplet structures observed using HAXPES for Eu(Rh 0.6 Co 0.4 ) 2 Si 2 and EuNi 2 (Si 1-x Ge x ) 2 (x = 0.70, 0.79, and 0.82) changes depending on temperature [12,13]. The temperature dependence of these structures has been sufficiently reproduced by a theoretical calculation based on the SIAM.…”

Section: Resultsmentioning

confidence: 99%

“…To understand the mechanism of temperature-induced valence transition, it is essential to discuss the changes of the 4f electronic state in EuT 2 X 2 . Recently, Ichiki et al have reported the Eu 3d states of EuNi 2 (Si 1-x Ge x ) 2 and Eu(Rh 1-x Co x ) 2 Si 2 observed by hard X-ray photoemission spectroscopy (HAXPES) [12,13]. The authors reproduced the experimental Eu 3d spectra using a theoretical analysis based on the single impurity Anderson model (SIAM) [14] and suggested that the hybridization strength between conduction and Eu 4f electrons (c-f hybridization strength, V cf ) and charge transfer energy (Δ) play an important role in the temperature-induced valence transition.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure of the Valence Transition System Eu(Rh₁₋_xT_x)₂Si₂ (T = Co, Ir) Studied by High-Energy Resolution Fluorescence Detection X-Ray Absorption Spectroscopy

Shimokasa

Kawamura

Taku

et al. 2020

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019)

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The electronic structure of Eu(Rh 1-x T x) 2 Si 2 (T = Co, Ir) showing a valence change with temperature has been investigated by means of high-energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS). The Eu L 3-edge HERFD-XAS spectra for Eu(Rh 1-x T x) 2 Si 2 distinctly demonstrate that, due to the improvement of the energy resolution, the intensities of Eu 2+ and Eu 3+ components are dependent on temperature. Each component has additional fine structures, which clearly change above and below the transition temperature. These spectral changes are similar to those for EuNi 2 (Si 1-x Ge x) 2 , but the degree of temperature dependence on energy difference between Eu 2+ and Eu 3+ components is different from EuNi 2 (Si 1-x Ge x) 2. The results of this study suggest that a treatment of the many-body interaction is essential to understanding the valence transition of Eu compounds.

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Hard x-ray photoemission study of the temperature-induced valence transition systemEuNi2(Si1−xGex)2

Cited by 10 publications

References 33 publications

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Pressure influence on the valence and magnetic state of Yb ions in noncentrosymmetric heavy-fermion YbNiC2

Electronic Structure of the Valence Transition System Eu(Rh₁₋_xT_x)₂Si₂ (T = Co, Ir) Studied by High-Energy Resolution Fluorescence Detection X-Ray Absorption Spectroscopy

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Hard x-ray photoemission study of the temperature-induced valence transition systemEuNi2(Si1−xGex)2

Cited by 10 publications

References 33 publications

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Pressure influence on the valence and magnetic state of Yb ions in noncentrosymmetric heavy-fermion YbNiC2

Electronic Structure of the Valence Transition System Eu(Rh1−xTx)2Si2 (T = Co, Ir) Studied by High-Energy Resolution Fluorescence Detection X-Ray Absorption Spectroscopy

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Electronic Structure of the Valence Transition System Eu(Rh₁₋_xT_x)₂Si₂ (T = Co, Ir) Studied by High-Energy Resolution Fluorescence Detection X-Ray Absorption Spectroscopy