Orbital characters determined from Fermi surface intensity patterns using angle-resolved photoemission spectroscopy

Wang, Xiaoping; Richard, P.; Huang, Yaobo; Miao, H.; Cevey, Le; Xu, Na; Sun, Yujuan; Qian, Tian; Xu, Yiming; Shi, M.; Hu, Jiangping; Dai, Xi; Ding, Hong

doi:10.1103/physrevb.85.214518

Cited by 58 publications

(57 citation statements)

References 47 publications

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“…Taken together, the relevant electrons in the FeSCs are more delocalized than in the cuprates and effectively give rise to smaller electronic correlation effects. In this context, it is also interesting to note that the calculated band structure [69][70][71][72] agrees well (not in all, but in many cases) with the one determined by ARPES [73][74][75] and quantum oscillation measurements [76,77], which can be interpreted as another evidence for weaker correlation effects in FeSCs.…”

Section: Structural and Normal-state Propertiessupporting

confidence: 65%

“…Here,Ô ch k denotes the respective bosonic operators defined in (75), and the corresponding eigenmode f ch i (k) gives detailed information on the real-space ordering pattern (see Appendix 6.4) as well as on the one-particle spectrum within the symmetry broken phase. At sufficiently low energy scales of the flow, the four-point function γ (4) or, respectively, the coupling function V Λ starts to diverge and thus signals the possible onset of spontaneous symmetry breaking.…”

Section: Channel Decoupling and Order Parametersmentioning

confidence: 99%

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Functional renormalization group for multi-orbital Fermi surface instabilities

Platt

Hanke

Thomale

2013

Advances in Physics

196

253

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Technological progress in material synthesis, as well as artificial realization of condensed matter scenarios via ultra-cold atomic gases in optical lattices or epitaxial growth of thin films, is opening the gate to investigate a plethora of unprecedented strongly correlated electron systems. In a large subclass thereof, a metallic state of layered electrons undergoes an ordering transition below some temperature into unconventional states of matter driven by electronic correlations, such as magnetism, superconductivity, or other Fermi surface instabilities. While this type of phenomena has been a well-established direction of research in condensed matter for decades, the variety of today's accessible scenarios pose fundamental new challenges to describe them. A core complication is the multi-orbital nature of the low-energy electronic structure of these systems, such as the multi-d orbital nature of electrons in iron pnictides and transition-metal oxides in general, but also electronic states of matter on lattices with multiple sites per unit cell such as the honeycomb or kagome lattice. In this review, we propagate the functional renormalization group (FRG) as a suited approach to investigate multi-orbital Fermi surface instabilities. The primary goal of the review is to describe the FRG in explicit detail and render it accessible to everyone both at a technical and intuitive level. Summarizing recent progress in the field of multi-orbital Fermi surface instabilities, we illustrate how the unbiased fashion by which the FRG treats all kinds of ordering tendencies guarantees an adequate description of electronic phase diagrams and often allows to obtain parameter trends of sufficient accuracy to make qualitative predictions for experiments. This review includes detailed and illustrative illustrations of magnetism and, in particular, superconductivity for the iron pnictides from the viewpoint of FRG. Furthermore, it discusses candidate scenarios for topological bulk singlet superconductivity and exotic particle-hole condensates on hexagonal lattices such as sodium-doped cobaltates, graphene doped to van Hove filling, and the kagome Hubbard model. In total, the FRG promises to be one of the most versatile and revealing numerical approaches to address unconventional Fermi surface instabilities in future fields of condensed matter research.

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Section: Structural and Normal-state Propertiessupporting

confidence: 65%

Section: Channel Decoupling and Order Parametersmentioning

confidence: 99%

Functional renormalization group for multi-orbital Fermi surface instabilities

Platt

Hanke

Thomale

2013

Advances in Physics

196

253

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“…The α, β, γ, δ, and δ bands are dominated by similar orbitals in K x Fe 2−y Se 2 and other iron-based superconductors [27,28]. However, the δ and δ bands are weakly hybridized in K x Fe 2−y Se 2 , instead of being strongly hybridized in the other iron-based superconductors.…”

Section: Discussionmentioning

confidence: 82%

“…Polarization-dependent ARPES experiments have been conducted extensively on the iron-based superconductors, including LaOFeAs [13], BaFe 2 As 2 [23][24][25][26][27], NaFeAs [28,29], and FeTe [17,27]. Here we report the polarization-dependent ARPES study on the orbital characters of K x Fe 2−y Se 2 superconductor.…”

mentioning

confidence: 99%

The orbital characters of low-energy electronic structure in iron-chalcogenide superconductor K x Fe2−y Se2

Chen

et al. 2012

Chin. Sci. Bull.

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“…To quantify the k z effect of the a band and confirm that it does not cross E F along k z , we extract the NS dispersion of the a band at k z ¼ 0 and p. Figure 3a,c shows the ARPES intensity plots of 3% Co at 51 eV (k z ¼ 0) and 35 eV (k z ¼ p), respectively. The data are recorded at 20 K with linearly polarized light to enhance the intensity of the a band 11,17 . The intensity plots and EDCs show that the band top of the a band has tiny dispersion along k z and prove that at least for 3% Co, the a band is completely sinking below E F all over the momentum space.…”

Section: Resultsmentioning

confidence: 99%

Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs

et al. 2015

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In conventional BCS superconductors, the quantum condensation of superconducting electron pairs is understood as a Fermi surface instability, in which the low-energy electrons are paired by attractive interactions. Whether this explanation is still valid in high-T c superconductors such as cuprates and iron-based superconductors remains an open question. In particular, a fundamentally different picture of the electron pairs, which are believed to be formed locally by repulsive interactions, may prevail. Here we report a high-resolution angle-resolved photoemission spectroscopy study on LiFe 1 À x Co x As. We reveal a large and robust superconducting gap on a band sinking below the Fermi level on Co substitution. The observed Fermi-surface-free superconducting order is also the largest over the momentum space, which rules out a proximity effect origin and indicates that the order parameter is not tied to the Fermi surface as a result of a surface instability.

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Orbital characters determined from Fermi surface intensity patterns using angle-resolved photoemission spectroscopy

Cited by 58 publications

References 47 publications

Functional renormalization group for multi-orbital Fermi surface instabilities

Functional renormalization group for multi-orbital Fermi surface instabilities

The orbital characters of low-energy electronic structure in iron-chalcogenide superconductor K x Fe2−y Se2

Observation of strong electron pairing on bands without Fermi surfaces in LiFe1−xCoxAs

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