scholarly journals Orbital character and electron correlation effects on two- and three-dimensional Fermi surfaces in KFe2As2 revealed by angle-resolved photoemission spectroscopy

2014 ◽  
Vol 2 ◽  
Author(s):  
Teppei Yoshida ◽  
Shin-Ichiro Ideta ◽  
Ichiro Nishi ◽  
Atsushi Fujimori ◽  
Ming Yi ◽  
...  
Keyword(s):  
Electron Correlation ◽  
Three Dimensional ◽  
Photoemission Spectroscopy ◽  
Correlation Effects ◽  
Fermi Surfaces ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Electron Correlation Effects ◽  
Orbital Character

scholarly journals Observation of a remarkable reduction of correlation effects in BaCr2As2 by ARPES

2017 ◽  
Vol 114 (47) ◽  
pp. 12425-12429 ◽  
Author(s):  
Jayita Nayak ◽  
Kai Filsinger ◽  
Gerhard H. Fecher ◽  
Stanislav Chadov ◽  
Ján Minár ◽  
...  
Keyword(s):  
Exchange Interaction ◽  
Electron Correlation ◽  
Electron Shell ◽  
Correlation Effect ◽  
Correlation Effects ◽  
Unconventional Superconductors ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Theoretical Predictions ◽  
Electron Correlation Effects ◽  
Remarkable Reduction

The superconducting phase in iron-based high-Tc superconductors (FeSC), as in other unconventional superconductors such as the cuprates, neighbors a magnetically ordered one in the phase diagram. This proximity hints at the importance of electron correlation effects in these materials, and Hund’s exchange interaction has been suggested to be the dominant correlation effect in FeSCs because of their multiband nature. By this reasoning, correlation should be strongest for materials closest to a half-filled 3d electron shell (Mn compounds, hole-doped FeSCs) and decrease for systems with both higher (electron-doped FeSCs) and lower (Cr-pnictides) 3d counts. Here we address the strength of correlation effects in nonsuperconducting antiferromagnetic BaCr2As2 by means of angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations. This combination provides us with two handles on the strength of correlation: First, a comparison of the experimental and calculated effective masses yields the correlation-induced mass renormalization. In addition, the lifetime broadening of the experimentally observed dispersions provides another measure of the correlation strength. Both approaches reveal a reduction of electron correlation in BaCr2As2 with respect to systems with a 3d count closer to five. Our results thereby support the theoretical predictions that Hund’s exchange interaction is important in these materials.

scholarly journals Band-dependent superconducting gap in SrFe2(As0.65P0.35)2 studied by angle-resolved photoemission spectroscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
H. Suzuki ◽  
T. Kobayashi ◽  
S. Miyasaka ◽  
K. Okazaki ◽  
T. Yoshida ◽  
...  
Keyword(s):  
Order Parameter ◽  
Three Dimensional ◽  
Photoemission Spectroscopy ◽  
Superconducting Gap ◽  
Direct Identification ◽  
Fermi Surfaces ◽  
Iron Pnictide ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sign Change ◽  
Gap Structure

Abstract The isovalent-substituted iron pnictide compound SrFe2(As1−xPx)2 exhibits multiple evidence for nodal superconductivity via various experimental probes, such as the penetration depth, nuclear magnetic resonance and specific heat measurements. The direct identification of the nodal superconducting (SC) gap structure is challenging, partly because the presence of nodes is not protected by symmetry but instead caused by an accidental sign change of the order parameter, and also because of the three-dimensionality of the electronic structure. We have studied the SC gaps of SrFe2(As0.65P0.35)2 in three-dimensional momentum space by synchrotron and laser-based angle-resolved photoemission spectroscopy. The three hole Fermi surfaces (FSs) at the zone center have SC gaps with different magnitudes, whereas the SC gaps of the electron FSs at the zone corner are almost isotropic and kz-independent. As a possible nodal SC gap structure, we propose that the SC gap of the outer hole FS changes sign around the Z-X [(0, 0, 2π) − (π, π, 2π)] direction.

Quantifying electron-correlation effects in small coinage-metal clusters by ab initio calculations

2021 ◽  
Author(s):  
Victor Giovanni de Pina ◽  
Bráulio Gabriel Alencar Brito ◽  
Guo -Q Hai ◽  
Ladir Cândido
Keyword(s):  
Monte Carlo ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Correlation ◽  
Metal Clusters ◽  
Correlation Effects ◽  
Diffusion Monte Carlo ◽  
Coinage Metal ◽  
Electron Correlation Effects ◽  
Fixed Node

We investigate many-electron correlation effects in neutral and charged coinage-metal clusters Cun, Agn, and Aun (n = 1 − 4) by ab initio calculations using fixed-node diffusion Monte Carlo (FN-DMC)...

BS DFT and BS HDFT studies of CrCr sextuple bond from the viewpoint of electron correlation effects

2009 ◽  
Vol 109 (14) ◽  
pp. 3315-3324 ◽  
Author(s):  
Yasutaka Kitagawa ◽  
Yasuyuki Nakanishi ◽  
Toru Saito ◽  
Takashi Kawakami ◽  
Mitsutaka Okumura ◽  
...  
Keyword(s):  
Electron Correlation ◽  
Correlation Effects ◽  
Electron Correlation Effects

Nonnuclear Maxima in the Charge Density

1993 ◽  
Vol 48 (1-2) ◽  
pp. 127-133 ◽  
Author(s):  
Kenneth E. Edgecombe ◽  
Vedene H. Smith, Jr. ◽  
Florian Müller-Plathe
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Electron Correlation ◽  
Basis Set ◽  
Valence Shell ◽  
Correlation Effects ◽  
Electron Correlation Effects

Abstract Basis-set and electron-correlation effects on the appearance and disappearance of nonnuclear maxima in the electron density are examined in Li2 , Na2 , Na4 and Na5 . It is shown that nonnuclear attractors can be removed in all cases except Li2 . The appearance of a pseudoatom in a lithium molecule correlates remarkably well with the size of the region, in an atomic calculation, of V2r(r) for the valence shell of the atom. This and the fact that the pseudoatom is also present in the promolecule indicate that the pseudoatoms are remnants of, or in fact are portions of, atoms that are not perturbed enough in the molecule to remove an essentially atomic characteristic.

Sign in / Sign up

Export Citation Format

Share Document