ARPES study of the effect of Cu substitution on the electronic structure of NaFeAs

Cui, Shengtao; Kong, Shuang; Ju, Sailong; Wu, Peiheng; Wang, A. F.; Luo, X. G.; Chen, X. H.; Zhang, G. B.; Sun, Zhe

doi:10.1103/physrevb.88.245112

Cited by 22 publications

(31 citation statements)

References 32 publications

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“…That means the decrease in the hole pocket size is relatively low compared to the increase in the electron pocket. This observation is not supporting the experimental [19][20][21][22][23]25,30,31] and theoretical [17,24,62] reports on weakly correlated 122-type and 111-type compounds, which suggests that in going from the substitution of Co to Ni to Cu to Zn in the place of Fe, the volume of the Fermi sheets increases and decreases, which is qualitatively consistent with the rigid-band model.…”

Section: Discussioncontrasting

confidence: 42%

“…Many ARPES studies, dealing with the effect of impurities on the electronic structure, are available on weakly correlated 122-type [20][21][22][23]28] and 111-type [29][30][31] iron pnictides. Intriguingly, till now, no ARPES study has been made on the more correlated charge doped 11-type iron chalcogenides, which motivated us for the present study, though there are transport [32][33][34][35], thermal [36], and magnetic measurements [37] reporting on this issue.…”

Section: Introductionmentioning

confidence: 99%

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Effect of impurity substitution on band structure and mass renormalization of the correlatedFeTe0.5Se0.5superconductor

et al. 2016

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Using angle-resolved photoemission spectroscopy (ARPES), we studied the effect of the impurity potential on the electronic structure of FeTe 0.5 Se 0.5 superconductor by substituting 10% of Ni for Fe, which leads to an electron doping of the system. We could resolve three hole pockets near the zone center and an electron pocket near the zone corner in the case of FeTe 0.5 Se 0.5 , whereas only two hole pockets near the zone center and an electron pocket near the zone corner are resolved in the case of Fe 0.9 Ni 0.1 Te 0.5 Se 0.5 , suggesting that the hole pocket having predominantly the xy orbital character is very sensitive to the impurity scattering. Upon electron doping, the size of the hole pockets decreases and the size of the electron pockets increases as compared to the host compound. However, the observed changes in the size of the electron and hole pockets are not consistent with the rigid-band model. Moreover, the effective mass of the hole pockets is reduced near the zone center and of the electron pockets is increased near the zone corner in the doped Fe 0.9 Ni 0.1 Te 0.5 Se 0.5 as compared to FeTe 0.5 Se 0.5 . We refer these observations to the changes of the spectral function due to the effect of the impurity potential of the dopants.

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Section: Discussioncontrasting

confidence: 42%

Section: Introductionmentioning

confidence: 99%

Effect of impurity substitution on band structure and mass renormalization of the correlatedFeTe0.5Se0.5superconductor

et al. 2016

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“…On the contrary, the occupancy increases with increasing x in the electron doping region with u=5.4 eV. The ARPES experiment on NaFeAs 17 indicates that the total number of electron carriers introduced by Cu atoms increases when the Cu substitution increases from 0.019 to 0.14. However, the average number of electrons in Cu atom decreases significantly from 1.9 to 0.64 with increasing doping concentration.…”

Section: 54mentioning

confidence: 99%

“…16 Such an observation was also supported by the ARPES study, which exhibited the increasing of the Fermi level in NaFe 1−x Cu x As, indicating a fraction of electron doping introduced by the Cu dopant. 17 Up to date, the dispute on the electron or hole doping in the 111 and 122 phases is far from resolved. Therefore, further investigations are needed to explain the reason why the Cu substitution plays different roles in NaFe 1−x Cu x As and Ba(Fe 1−x Cu x ) 2 As 2 compounds.…”

Section: -15mentioning

confidence: 99%

Localization and orbital selectivity in iron-based superconductors with Cu substitution

Liu

Wang

et al. 2015

Phys. Rev. B

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We study an inhomogeneous three-orbital Hubbard model for the Cu-substituted iron pnictides using an extended real-space Green's function method combined with density functional calculations. We find that the onsite interactions of the Cu ions are the principal determinant of whether an electron dopant or a hole dopant is caused by the Cu substitution. It is found that the Cu substitution could lead to a hole doping when its onsite interactions are smaller than a critical value, as opposed to an electron doping when the interactions of Cu ions are larger than the critical value, which may explain why the effects of Cu substitution on the carrier density are entirely different in NaFe1−xCuxAs and Ba(Fe1−xCux)2As2. We also find that the effect of a doping-induced disorder is considerable in the Cu-substituted iron pnictides, and its cooperative effect with electron correlations contributes to the orbital-selective insulating phases in NaFe1−xCuxAs and Ba(Fe1−xCux)2As2.

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“…x Cu x As with x up to 0.14 showed that, except for introducing extra charge carriers, the overall band dispersion barely changes with Cu doping, and the Fermi surface and/or all the energy bands near E F are dominated by Fe 3d orbitals [35]. It is of high interest to reveal the momentum-resolved electronic structure with ARPES in order to get further insight into the evolution of the Cu 3d-derived electronic states at or near E F , as the long-range AFM-ordered insulator evolves into a metallic or superconducting state with decreasing the concentration of the Cu dopant in NaFe 1-…”

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confidence: 99%

NaFe0.56Cu0.44As: A Pnictide Insulating Phase Induced by On-Site Coulomb Interaction

Matt

et al. 2016

Phys. Rev. Lett.

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In the studies of iron-pnictides, a key question is whether their bad-metal state from which the superconductivity emerges lies in close proximity with a magnetically ordered insulating phase. Recently it was found that at low temperatures, the heavily Cu-doped NaFe1-xCuxAs (x > 0.3) iron-pnictide is an insulator with long-range antiferromagnetic order, similar to the parent compound of cuprates but distinct from all other iron-pnictides. Using angle-resolved photoemission spectroscopy, we determined the momentum-resolved electronic structure of NaFe1-xCuxAs (x = 0.44) and identified that its ground state is a narrow-gap insulator. Combining the experimental results with density functional theory (DFT) and DFT+U calculations, our analysis reveals that the on-site Coulombic (Hubbard) and Hund's coupling energies play crucial roles in formation of the band gap about the chemical potential. We propose that at finite temperatures charge carriers are thermally excited from the Cu-As-like valence band into the conduction band, which is of Fe 3d-like character. With increasing temperature, the number of electrons in the conduction band becomes larger and the hopping energy between Fe sites increases, and finally the long-range antiferromagnetic order is destroyed at T > TN. Our study provides a basis for investigating the evolution of the electronic structure of a Mott insulator transforming into a bad metallic phase, and eventually forming a superconducting state in iron-pnictides.

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ARPES study of the effect of Cu substitution on the electronic structure of NaFeAs

Cited by 22 publications

References 32 publications

Effect of impurity substitution on band structure and mass renormalization of the correlatedFeTe0.5Se0.5superconductor

Effect of impurity substitution on band structure and mass renormalization of the correlatedFeTe0.5Se0.5superconductor

Localization and orbital selectivity in iron-based superconductors with Cu substitution

NaFe0.56Cu0.44As: A Pnictide Insulating Phase Induced by On-Site Coulomb Interaction

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