The anomalous electronic structure of electron-doped cuprate superconductors by considering the next higher harmonics of the superconducting gap

2021 ◽  
pp. 2150256
Author(s):  
Jihong Qin
Keyword(s):  
Electron Spectrum ◽  
Cuprate Superconductors ◽  
Mean Field Theory ◽  
Mean Field ◽  
Anomalous Behavior ◽  
Momentum Dependence ◽  
Higher Harmonics ◽  
Critical Strength ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Energy And Momentum

Based on the self-consistent mean field theory by considering the next higher harmonics of the superconducting (SC) gap, we discuss the energy and momentum dependence of the electron spectrum in electron-doped cuprate superconductors. By calculation of the electron spectral function, it is shown that the weight of the electron spectrum at the Fermi energy is strongly redistributed by the next higher harmonics of the SC gap in electron-doped cuprate superconductors, especially for the antinodal region. At the antinodal region, the weight of the electron spectrum at the Fermi surface increases with the increase of next higher harmonics term, reaches the maximum at a critical strength, then decreases when the next higher harmonics is larger. Our theoretical results show that the variation of the SC gap with the next higher harmonics can explain the anomalous behavior of the electron spectrum and different angle-resolved photoemission spectroscopy experimental results of different samples of electron-doped cuprate superconductors. Moreover, the magnitude of the SC gap can be suppressed by the next higher harmonics, which may be one of the reasons for the smaller SC gap in electron-doped cuprate superconductors. Obvious topological change happens in the SC gap at a critical strength of the next higher harmonics.

Doping dependence of unusual electron spectrum in hole-doped cuprate superconductors

2016 ◽  
Vol 30 (04) ◽  
pp. 1650032 ◽  
Author(s):  
Shuhua Wang ◽  
Bingchen Han ◽  
Xiaomin Lü ◽  
Feng Yuan ◽  
Huaisong Zhao
Keyword(s):  
Electron Spectrum ◽  
Doping Concentration ◽  
Cuprate Superconductors ◽  
Mean Field Theory ◽  
Mean Field ◽  
Superconducting Order Parameter ◽  
Doping Dependence ◽  
Renormalization Factor ◽  
Underdoped Region ◽  
Self Consistent

Based on the renormalized Hubbard model, the doping dependence of electron spectrum in cuprate superconductors is discussed within the self-consistent mean field theory. It is shown that the renormalization factor [Formula: see text] (then the quasiparticle coherent weight) increases almost linearly with the doping and plays an important role in the unconventional superconductivity for cuprate superconductors. It suppresses the magnitude of the quasiparticle peak in the electron spectrum, especially in underdoped region. By calculation of the energy and doping dependence of the electron spectral function, the main features of the electron spectrum in cuprate superconductors can be described qualitatively. In particular, with the increasing doping concentration, the position of the quasiparticle peak moves to the Fermi energy and the magnitude of the quasiparticle peak increases monotonically. Our results also show that the superconducting order parameter is determined by product of the renormalization factor and the pseudogap.

scholarly journals Evolution of the Kondo lattice electronic structure above the transport coherence temperature

2020 ◽  
Vol 117 (38) ◽  
pp. 23467-23476
Author(s):  
Sooyoung Jang ◽  
J. D. Denlinger ◽  
J. W. Allen ◽  
V. S. Zapf ◽  
M. B. Maple ◽  
...  
Keyword(s):  
Electric Field ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spectral Weight ◽  
Kondo Lattice ◽  
Crystalline Electric Field ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sufficient Detail ◽  
Arpes Data

The temperature-dependent evolution of the Kondo lattice is a long-standing topic of theoretical and experimental investigation and yet it lacks a truly microscopic description of the relation of the basic f-c hybridization processes to the fundamental temperature scales of Kondo screening and Fermi-liquid lattice coherence. Here, the temperature dependence of f-c hybridized band dispersions and Fermi-energy f spectral weight in the Kondo lattice system CeCoIn5is investigated using f-resonant angle-resolved photoemission spectroscopy (ARPES) with sufficient detail to allow direct comparison to first-principles dynamical mean-field theory (DMFT) calculations containing full realism of crystalline electric-field states. The ARPES results, for two orthogonal (001) and (100) cleaved surfaces and three different f-c hybridization configurations, with additional microscopic insight provided by DMFT, reveal f participation in the Fermi surface at temperatures much higher than the lattice coherence temperature,T*≈45K, commonly believed to be the onset for such behavior. The DMFT results show the role of crystalline electric-field (CEF) splittings in this behavior and a T-dependent CEF degeneracy crossover belowT*is specifically highlighted. A recent ARPES report of low T Luttinger theorem failure for CeCoIn5is shown to be unjustified by current ARPES data and is not found in the theory.

scholarly journals RECENT ADVANCES IN UNCONVENTIONAL DENSITY WAVES

2004 ◽  
Vol 18 (09) ◽  
pp. 327-344 ◽  
Author(s):  
BALÁZS DÓRA ◽  
KAZUMI MAKI ◽  
ATTILA VIROSZTEK
Keyword(s):  
Cuprate Superconductors ◽  
Mean Field Theory ◽  
Density Wave ◽  
Mean Field ◽  
Temperature Phase ◽  
Pseudogap Phase ◽  
Excitonic Insulator ◽  
Quasiparticle Motion ◽  
Low Temperature Phase ◽  
Electronic Ground

The unconventional density wave (UDW) was speculated on as a possible electronic ground state in the excitonic insulator in 1968. The recent surge of interest in UDW's is partly due to the proposal that the pseudogap phase in high Tc cuprate superconductors is a d-wave density wave (d-DW). Here we review our recent works on UDW's within the framework of mean field theory. In particular, we have shown that many properties of the low temperature phase (LTP) in α-( BEDT-TTF )2 MHg ( SCN )4, with M = K , Rb and Tl , are well characterized in terms of the unconventional charge density wave (UCDW). In this identification the Landau quantization of the quasiparticle motion in a magnetic field (the Nersesyan effect) plays the crucial role. Indeed, the angle-dependent magnetoresistance and the negative giant Nernst effect are two hallmarks of UDW's.

scholarly journals Direct observation of kink evolution due to Hund’s coupling on approach to metal-insulator transition in NiS2−xSex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bo Gyu Jang ◽  
Garam Han ◽  
Ina Park ◽  
Dongwook Kim ◽  
Yoon Young Koh ◽  
...  
Keyword(s):  
Direct Observation ◽  
Density Functional ◽  
Temperature Scale ◽  
Characteristic Temperature ◽  
Mean Field Theory ◽  
Mean Field ◽  
Energy Scale ◽  
Low Energy ◽  
Characteristic Energy ◽  
Angle Resolved Photoemission Spectroscopy

AbstractUnderstanding characteristic energy scales is a fundamentally important issue in the study of strongly correlated systems. In multiband systems, an energy scale is affected not only by the effective Coulomb interaction but also by the Hund’s coupling. Direct observation of such energy scale has been elusive so far in spite of extensive studies. Here, we report the observation of a kink structure in the low energy dispersion of NiS2−xSex and its characteristic evolution with x, by using angle resolved photoemission spectroscopy. Dynamical mean field theory calculation combined with density functional theory confirms that this kink originates from Hund’s coupling. We find that the abrupt deviation from the Fermi liquid behavior in the electron self-energy results in the kink feature at low energy scale and that the kink is directly related to the coherence-incoherence crossover temperature scale. Our results mark the direct observation of the evolution of the characteristic temperature scale via kink features in the spectral function, which is the hallmark of Hund’s physics in the multiorbital system.

scholarly journals Systematic beyond-DFT study of binary transition metal oxides

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Subhasish Mandal ◽  
Kristjan Haule ◽  
Karin M. Rabe ◽  
David Vanderbilt
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Density Functional ◽  
Mean Field Theory ◽  
Mean Field ◽  
Photoemission Spectroscopy ◽  
Dft Methods ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Arpes Data

AbstractVarious methods going beyond density functional theory (DFT), such as DFT+U, hybrid functionals, meta-GGAs, GW, and DFT-embedded dynamical mean field theory (eDMFT), have been developed to describe the electronic structure of correlated materials, but it is unclear how accurate these methods can be expected to be when applied to a given strongly correlated solid. It is thus of pressing interest to compare their accuracy as they apply to different categories of materials. Here we introduce a novel paradigm in which a chosen set of beyond-DFT methods is systematically and uniformly tested on a chosen class of materials. For a first application, we choose the target materials to be the binary transition metal oxides FeO, CoO, MnO, and NiO in their antiferromagnetic phase and present a head-to-head comparison of spectral properties as computed using the various methods. We also compare with available experimental angle-resolved photoemission spectroscopy (ARPES), inverse-photoemission spectroscopy, and with optical absorption. For the class of compounds studied here, we find that both B3LYP and eDMFT reproduce the experiments quite well, with eDMFT doing best, in particular when comparing with the ARPES data.

Mean field theory of n-layer unbinding

1993 ◽  
Vol 3 (3) ◽  
pp. 385-393 ◽  
Author(s):  
W. Helfrich
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field
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