Evidence for momentum-dependent heavy-fermionic electronic structures: Soft x-ray ARPES for the superconductor 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>CeNi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Ge</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
 in the normal state

Nakatani, Y.; Aratani, H.; Fujiwara, H.; Mori, T.; Tsuruta, Akihiro; Tachibana, Shigeaki; Yamaguchi, Takashi; Yamasaki, Akira; Yasui, Akira; Yamagami, Hiroshi; Miyawaki, Jun; Ebihara, Takao; Saitoh, Y.; Sekiyama, A.

doi:10.1103/physrevb.97.115160

“…This result suggests that the change in the electronic structure starts at a much higher temperature than T K . A similar thermal effect in the σ(ω) spectra has been reported from ARPES results of CeNi 2 Ge 2 [7], YbRh 2 Si 2 [43], and CeCoIn 5 [11].…”

Section: Discussionsupporting

confidence: 83%

“…Since the effective carrier mass can be described as m * = kdk/dE(k)| k=k F of the dispersion curve of the conduction band E(k), where k is the wavenumber, the band dispersion is expected to be modified with temperature. Whereas the change of the density of states of the conduction band is contained in the optical conductivity (σ(ω)) and scanning tunneling spectroscopy measurements [2], the band dispersions E(k) can be directly detected by angle-resolved photoelectron spectroscopy (ARPES), which is a method now being widely used in HF materials [3,4,5,6,7]. However, since ARPES is very sensitive to solid surfaces due to low-energy electrons' detection, the results are sometimes inconsistent with bulk properties such as transport.…”

Section: Introductionmentioning

confidence: 99%

Optical evidence of local and itinerant states in Ce- and Yb-heavy-fermion compounds

Kimura

¹

,

Kwon

²

,

Krellner

³

et al. 2021

Preprint

0

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The electronic properties of Cerium (Ce) and ytterbium (Yb) intermetallic compounds may display a more local or more itinerant character depending on the interplay of the exchange interactions among the 4f electrons and the Kondo coupling between 4f and conduction electrons. For the more itinerant case, the materials form heavy-fermions once the Kondo effect is developed at low temperatures. Hence, a temperature variation occurs in the electronic structure that can be traced by investigating the optical conductivity (σ(ω)) spectra. Remarkably, the temperature variation in the σ(ω) spectrum is still present in the more localized case, even though the Kondo effect is strongly suppressed. Here, we clarify the local and itinerant character in the electronic structure by investigating the temperature dependence in the σ(ω) spectra of various Ce and Yb compounds with a tetragonal ThCr 2 Si 2 -type crystal structure. We explain the temperature change in a unified manner. Above temperatures of about 100 K, the temperature dependence of the σ(ω) spectra is mainly due to the electron-phonon interaction, while the temperature dependence below is due to the Kondo effect.

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“…Since the effective carrier mass can be described as m * = k dk/dE(k)| k=k F of the dispersion curve of the conduction band E(k), where k is the wavenumber, the band dispersion is expected to be modified with temperature. Whereas the change of the density of states of the conduction band is contained in the optical conductivity (σ(ω)) and scanning tunneling spectroscopy measurements [2], the band dispersions E(k) can be directly detected by angle-resolved photoelectron spectroscopy (ARPES), which is a method now being widely used in HF materials [3][4][5][6][7]. However, since ARPES is very sensitive to solid surfaces due to low-energy electrons' detection, the results are sometimes inconsistent with bulk properties such as transport.…”

Section: Introductionmentioning

confidence: 99%

Optical evidence of local and itinerant states in Ce- and Yb-heavy-fermion compounds

Kimura¹,

Kwon²,

Krellner³

et al. 2021

View full text Add to dashboard Cite

The electronic properties of Cerium (Ce) and ytterbium (Yb) intermetallic compounds may display a more local or more itinerant character depending on the interplay of the exchange interactions among the 4f electrons and the Kondo coupling between 4f and conduction electrons. For the more itinerant case, the materials form heavy-fermions once the Kondo effect is developed at low temperatures. Hence, a temperature variation occurs in the electronic structure that can be traced by investigating the optical conductivity (σ(ω)) spectra. Remarkably, the temperature variation in the σ(ω) spectrum is still present in the more localized case, even though the Kondo effect is strongly suppressed. Here, we clarify the local and itinerant character in the electronic structure by investigating the temperature dependence in the σ(ω) spectra of various Ce and Yb compounds with a tetragonal ThCr 2 Si 2 -type crystal structure. We explain the temperature change in a unified manner. Above temperatures of about 100 K, the temperature dependence of the σ(ω) spectra is mainly due to the electron-phonon interaction, while the temperature dependence below is due to the Kondo effect.

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“…Later, it was observed that the Kondo peak is intensive at Fermi vectors [8]. Finally, it was shown that bands, which are strongly correlated with 4f electrons, coexist with those weakly correlated within a single heavy fermion system [9] and that hybridization changes with momentum [10]. In fact, anisotropic structure of V cf is a source of a Kondo resonance intensity variation along the Fermi surface (FS), which is due to a particular distribution of f-electron density in reciprocal space.…”

Section: Introductionmentioning

confidence: 99%

Photoemission signature of momentum-dependent hybridization in CeCoIn$_5$

Kurleto,

Fidrysiak,

Nicolaï

et al. 2021

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0

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The hybridization between f-electrons and conduction band carriers (V cf ) is essential for the heavy fermion behavior and may play an important role in other fascinating phenomena such as quantum phase transitions or unconventional superconductivity. In order to provide an insight into V cf , systematic studies of CeCoIn 5 heavy fermion superconductor have been performed by angle-resolved photoemission spectroscopy (ARPES) in large angular range at temperature of T=6 K. Calculations carried out with relativistic multiple scattering KKR method and one-step model of photoemission yielded realistic simulation of the ARPES spectra. Effects of the hybridization strongly depend on wave vector. They include a dispersion of heavy f-electron band and a coexistence of highly and weakly correlated carriers. We have also observed a considerable variation of f-electron spectral weight at E F , which is normally determined by both the matrix element effects and wave vector dependentFermi surface scans covering a few Brillouin zones revealed large matrix element effects. A symmetrization of experimental FS, which reduces matrix element contribution, yielded a specific variation of 4f-electron spectral intensity at E F around Γ and M points, which is attributed to the effect of V cf hybridization. Tight binding approximation calculations for Ce-In plane provided the same universal distribution of 4f-electron density for a range of values of the parameters used in the model. This proves that we were able to extract the effect of V cf on f-electron intensity in ARPES spectra.

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Evidence for momentum-dependent heavy-fermionic electronic structures: Soft x-ray ARPES for the superconductor CeNi2Ge2 in the normal state

Cited by 9 publications

References 54 publications

Optical evidence of local and itinerant states in Ce- and Yb-heavy-fermion compounds

Optical evidence of local and itinerant states in Ce- and Yb-heavy-fermion compounds

Optical evidence of local and itinerant states in Ce- and Yb-heavy-fermion compounds

Photoemission signature of momentum-dependent hybridization in CeCoIn$_5$

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