Fermiology, orbital order, orbital fluctuations, and Cooper pairing in iron-based superconductors

Yang, Fan; Wang, Fa; Lee, Dung-Hai

doi:10.1103/physrevb.88.100504

Cited by 55 publications

(32 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, the strongcoupling approaches based on a localized spin picture, which can explain part of the observations, also face difficulties. The strong-coupling theories predict the s-wave superconducting state for AFS, [23][24][25] which is consistent with a fully gapped state but inconsistent with the observation of the spin resonance mode. 20) The situation is the same for orbitalfluctuation-mediated pairing theories, which predict signconserving s-wave states.…”

mentioning

confidence: 61%

Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

et al. 2016

View full text Add to dashboard Cite

One of the ultimate goals of the study of iron-based superconductors is to identify the common feature that produces the high critical temperature (T c ). In the early days, based on a weak-coupling viewpoint, the nesting between hole-and electron-like Fermi surfaces (FSs) leading to the so-called s± state was considered to be one such key feature. However, this theory has faced a serious challenge ever since the discovery of alkali-metal-doped FeSe (AFS) superconductors, in which only electron-like FSs with a nodeless superconducting gap are observed. Several theories have been proposed, but a consistent understanding is yet to be achieved. Here we show experimentally that a hole-like band exists in K x Fe 2−y Se 2 , which presumably forms a hole-like Fermi surface. The present study suggests that AFS can be categorized in the same group as iron arsenides with both hole-and electron-like FSs present. This result provides a foundation for a comprehensive understanding of the superconductivity in iron-based superconductors.

show abstract

mentioning

confidence: 61%

Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

et al. 2016

View full text Add to dashboard Cite

show abstract

“…This qualitative agreement becomes quantitative if one performs two typical for IBS transformations: orbital-dependent renormalizations and relative energy shift of the constructions in the center and the corner of the Brillouin Zone (BZ). While the former transformation is due to the Hund-rule coupling and is well captured by the DMFT calculations1011, the latter is not yet well understood, but can be related either to the so called s ± Pomeranchuk instability1213 or particle–hole asymmetry14. We note that such a shift, unlike the usually exercised “rigid” shift of the Fermi level, preserves the number of charge carriers in the system and results in singular Fermi surfaces in all known IBS e .…”

Section: Breakdown Of Tetragonal Symmetrymentioning

confidence: 85%

Effect of nematic ordering on electronic structure of FeSe

Fedorov

Yaresko

Kim

et al. 2016

Sci Rep

135

View full text Add to dashboard Cite

Electronically driven nematic order is often considered as an essential ingredient of high-temperature superconductivity. Its elusive nature in iron-based superconductors resulted in a controversy not only as regards its origin but also as to the degree of its influence on the electronic structure even in the simplest representative material FeSe. Here we utilized angle-resolved photoemission spectroscopy and density functional theory calculations to study the influence of the nematic order on the electronic structure of FeSe and determine its exact energy and momentum scales. Our results strongly suggest that the nematicity in FeSe is electronically driven, we resolve the recent controversy and provide the necessary quantitative experimental basis for a successful theory of superconductivity in iron-based materials which takes into account both, spin-orbit interaction and electronic nematicity.

show abstract

“…There exist many excellent review articles which address the main questions, theoretical models, and experimental results [6,[12][13][14][15][16][17][18][19][20][21][22]. In the following we provide an overview of the most relevant results for iron-based superconductors, and point the interested reader towards the aforementioned reviews for details.…”

Section: Iron-based Superconductivitymentioning

confidence: 99%

Discovery of orbital-selective Cooper pairing in FeSe

Sprau

Kostin

Kreisel

et al. 2017

Science

368

494

View full text Add to dashboard Cite

FeSe is the focus of intense research interest because of its unusual non-magnetic nematic state and because it forms the basis for achieving the highest critical temperatures of any iron-based superconductor. However, its Cooper pairing mechanism has not been determined because an accurate knowledge of the momentum-space structure of superconducting energy gaps ∆ i ( k) on the different electron-bands E i ( k) does not exist. Here we use Bogoliubov quasiparticle interference (BQPI) imaging to determine the coherent Fermi surface geometry of the α-and ε-bands surrounding the Γ = (0, 0) and X = (π/a Fe , 0) points of FeSe, and to measure their superconducting energy gaps ∆ α ( k) and ∆ ε ( k).We show directly that both gaps are extremely anisotropic but nodeless, and are aligned along orthogonal crystal axes. Moreover, by implementing a novel technique we demonstrate the sign change between ∆ α ( k) and ∆ ε ( k). This complex configuration of ∆ α ( k) and ∆ ε ( k), which was unanticipated within pairing theories for FeSe, reveals a unique form of superconductivity based on orbital selective Cooper pairing of electrons from the d yz orbitals of iron atoms. This new paradigm of orbital selectivity may be pivotal to understanding the microscopic interplay of quantum paramagnetism, nematicity and high temperature superconductivity. BIOGRAPHICAL SKETCHPeter Oliver Sprau was born on June 13th 1986 in the small town of Kirchheimbolanden, Germany, where he completed both his primary and secondary education. Long before he was a physicist, Peter was an active member of the track and field team in his school and a local club, even going on to compete in the dash and relay event on the state and federal youth level. Upon finishing school, he fulfilled his civic duty and carried out his alternative civilian service in the hospital in Kirchheimbolanden. While Peter's academic interests were diverse, including not just science but also Latin and history, his natural curiosity about the world finally urged him to pursue a higher education in physics. Mistakes. Make glorious, amazing mistakes. Make mistakes nobody's ever made before. Don't freeze, don't stop, don't worry that it isn't good enough, or it isn't perfect, whatever it is: art, or love, or work or family or life.Whatever it is you're scared of doing, Do it. Make your mistakes, next year and forever." I also want to acknowledge in no specific order the following people for useful discussions throughout my PhD:

show abstract

Fermiology, orbital order, orbital fluctuations, and Cooper pairing in iron-based superconductors

Cited by 55 publications

References 42 publications

Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

Effect of nematic ordering on electronic structure of FeSe

Discovery of orbital-selective Cooper pairing in FeSe

Contact Info

Product

Resources

About