Electronic structure and 
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-electron character in 
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 studied by angle-resolved photoemission spectroscopy

Yao, Qi; Kaczorowski, D.; Swatek, Przemysław; Gnida, D.; Wen, Chenhaoping; Niu, X. H.; Peng, Rui; Xu, H. C.; Dudin, Pavel; Kirchner, Stefan; Chen, Qiuyun; Shen, Dawei; Feng, D. L.

doi:10.1103/physrevb.99.081107

“…We have thus demonstrated that the QP mass renormalization and FL QP breakdown are orbitally selective along the Γ-S direction. It is also worth noticing that temperature dependent spectral weight has also been reported in CeCoIn 5 [57] and Ce 2 PdIn 8 [58]. This effect may therefore be generic to heavy fermion quasiparticles.…”

mentioning

confidence: 62%

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Sutter

¹

,

Kim

²

,

Matt

³

et al. 2019

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We present a comprehensive angle-resolved photoemission spectroscopy study of Ca1.8Sr0.2RuO4. Four distinct bands are revealed and along the Ru-O bond direction their orbital characters are identified through light polarisation analysis and comparison to dynamical mean field theory calculations. Bands assigned to dxz, dyz orbitals display Fermi liquid behavior with four-fold quasi particle mass renormalization. Extremely heavy Fermions -associated with a predominantly dxy band character -are shown to display non-Fermi liquid behavior. We thus demonstrate that Ca1.8Sr0.2RuO4 is a hybrid metal with an orbitally-selective Fermi liquid quasiparticle breakdown.Correlated metals are typically classified either as Fermi liquids or non-Fermi liquids depending on whether resistivity scales with temperature squared or not. There is, however, transport evidence suggesting that some materials are hybrids of these two metal classes [1]. This mixed regime is of particular interest as it provides insight into how Fermi liquids break down and the nature of non-Fermi liquid quasiparticles. In this context, multi-orbital metallic systems in conjunction with strong Hund's coupling and electron correlations are of great conceptual importance [2]. Such Hund's metals are expected to display orbital differentiated quasiparticle (QP) renormalization effects along with magnetic correlations [3]. In the strongly correlated limit, orbitally selective Mott physics (OSMP) has been explored theoretically [4][5][6][7][8][9]. The concepts of Hund's metals and OSMP have both been applied to describe band structure renormalization effects in pnictide superconductor compounds [10][11][12][13][14][15]. It remains, however, unclear whether these systems exhibit genuine heavy Fermion and Mott physics. In contrast, the oxide compounds LiV 2 O 4 and Ca 1.8 Sr 0.2 RuO 4 are multi-orbital systems where the existence of heavy Fermions are clearly demonstrated from specific heat measurements [16,17]. Ca 1.8 Sr 0.2 RuO 4 is furthermore in close proximity to a Mott-Hubbard metalinsulator transition [18]. Angle resolved-photoemission experiments (ARPES) on this system have been interpreted in terms of both the Hund's metal and the OSMP scenario [19,20]. Resistivity and specific heat indicate that the ground state is a Fermi liquid (FL). How-ever, a thermal excitation of just 1 K turns the system into a non-Fermi liquid (nFL) state [16]. Here we present a high-resolution ARPES study, demonstrating that Ca 1.8 Sr 0.2 RuO 4 is neither a standard Hunds metal nor representing OSMP. In fact, the thermally excited state constitutes an example of a hybrid metal. Along the Ru-O bond direction, bands with d xz , d yz orbital character display FL behavior whereas d xy dominated bands host nFL QPs. Breakdown of FL QPs are therefore orbitally selective. This physics might apply to other ruthenate systems such as for example Sr 3 Ru 2 O 7 .Single crystals of Ca 1.8 Sr 0.2 RuO 4 were grown by the flux-feeding floating-zone technique [30,31]. ARPES experiments were carried o...

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“…The difference between a clear Fano-line resonance and hybridization gap feature in Kondo lattices requires more theoretical investigations. On the other hand, heavy band formation has been suggested from angle-resolved photoemission studies to begin at temperatures much higher than the coherence temperature T * in several heavy fermion systems, such as CeCoIn 5 [45], CeIrIn 5 [46] and Ce 2 PdIn 8 [47]. This interpretation, however, could be influenced by Kondo scattering on excited crystal field levels and not be representative of formation of a heavymass ground state [48].…”

Section: Resultsmentioning

confidence: 99%

Point-contact spectroscopy of heavy fermion superconductors Ce₂PdIn₈ and Ce₃PdIn₁₁ in comparison with CeCoIn₅

Yin¹,

Che²,

Le³

et al. 2021

J. Phys.: Condens. Matter

4

0

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We report point-contact spectroscopy measurements on heavy fermion cousins CeCoIn5, Ce2PdIn8 and Ce3PdIn11 to systematically study the hybridization between f and conduction electrons. Below a temperature T*, the spectrum of each compound exhibits an evolving Fano-like conductance shape, superimposed on a sloping background, that suggests the development of hybridization between local f and itinerant conduction electrons in the coherent heavy fermion state below T*. We present a quantitative analysis of the conductance curves with a two-channel model to compare the tunneling process between normal metallic silver particles in our soft point-contact and heavy-fermion single crystals CeCoIn5, Ce2PdIn8 and Ce3PdIn11.

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“…The high-intensity flat band observed in all samples corresponds to the 𝑓 0 state prevalent in the Ce-based HFs material. [13][14][15][16][17][18][19][20][21]25] It can be observed that the location, intensity, and width of 𝑓 0 state vary greatly with materials. Weak heavy quasiparticle bands close to 𝐸 F are observed, 107402-3 corresponding to 𝑓 1 5/2 and 𝑓 1 7/2 final states.…”

mentioning

confidence: 99%

The 4f-Hybridization Strength in Ce_m M_n In_3m+2n Heavy-Fermion Compounds Studied by Angle-Resolved Photoemission Spectroscopy

Song¹,

Luo²,

Zhang³

et al. 2021

Chinese Phys. Lett.

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We systemically investigate the nature of Ce 4f electrons in structurally layered heavy-fermion compounds Ce m M n In3m + 2n (with M = Co, Rh, Ir, and Pt, m = 1, 2, n = 0–2), at low temperature using on-resonance angle-resolved photoemission spectroscopy. Three heavy quasiparticle bands f 0, f 7 / 2 1 and f 5 / 2 1 , are observed in all compounds, whereas their intensities and energy locations vary greatly with materials. The strong f 0 states imply that the localized electron behavior dominates the Ce 4f states. The Ce 4f electrons are partially hybridized with the conduction electrons, making them have the dual nature of localization and itinerancy. Our quantitative comparison reveals that the f 5 / 2 1 –f 0 intensity ratio is more suitable to reflect the 4f-state hybridization strength.

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Electronic structure and 4f -electron character in Ce2PdIn8 studied by angle-resolved photoemission spectroscopy

Cited by 14 publications

References 33 publications

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Point-contact spectroscopy of heavy fermion superconductors Ce₂PdIn₈ and Ce₃PdIn₁₁ in comparison with CeCoIn₅

The 4f-Hybridization Strength in Ce_m M_n In_3m+2n Heavy-Fermion Compounds Studied by Angle-Resolved Photoemission Spectroscopy

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Electronic structure and 4f -electron character in Ce2PdIn8 studied by angle-resolved photoemission spectroscopy

Cited by 14 publications

References 33 publications

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Point-contact spectroscopy of heavy fermion superconductors Ce2PdIn8 and Ce3PdIn11 in comparison with CeCoIn5

The 4f-Hybridization Strength in Ce m Mn In3m+2n Heavy-Fermion Compounds Studied by Angle-Resolved Photoemission Spectroscopy

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Point-contact spectroscopy of heavy fermion superconductors Ce₂PdIn₈ and Ce₃PdIn₁₁ in comparison with CeCoIn₅

The 4f-Hybridization Strength in Ce_m M_n In_3m+2n Heavy-Fermion Compounds Studied by Angle-Resolved Photoemission Spectroscopy