Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors

Pfau, Heike; Chen, Sudi; Yi, Ming; Hashimoto, M.; Rotundu, C. R.; Palmstrom, Johanna C.; Chen, T.; Dai, Pengcheng; Straquadine, Joshua; Hristov, Alexander T.; Birgeneau, R. J.; Fisher, I. R.; Lü, Donghui; Shen, Zhi‐Xun

doi:10.1103/physrevlett.123.066402

Cited by 55 publications

(57 citation statements)

References 62 publications

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“…Recently, evidence for the second pocket at the Y point has been reported in the literature as well [117,118] suggesting that a detailed understanding of this issue might also be related to shifts of the d xz and d yz orbital states in the orthorhombic state. Depending on the assignments of peaks in the measured spectral function to bands at the X-point, a large splitting of 50 meV [109,113,116,119] or much smaller splitting of 10 meV [107,110] has been deduced, while in both scenarios the sign of the splitting is reversed between the Γ point and the X point [106]-similar to findings in Ba122 [120]. The four branches of oscillation frequencies observed in quantum oscillations of the resistivity [92,121,122] correspond to the extremely small areas of the Fermi surface sheets covering only few percent of the Brillouin zone.…”

Section: Electronic Structure Of Fesesupporting

confidence: 73%

On the Remarkable Superconductivity of FeSe and Its Close Cousins

2020

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Emergent electronic phenomena in iron-based superconductors have been at the forefront of condensed matter physics for more than a decade. Much has been learned about the origins and intertwined roles of ordered phases, including nematicity, magnetism, and superconductivity, in this fascinating class of materials. In recent years, focus has been centered on the peculiar and highly unusual properties of FeSe and its close cousins. This family of materials has attracted considerable attention due to the discovery of unexpected superconducting gap structures, a wide range of superconducting critical temperatures, and evidence for nontrivial band topology, including associated spin-helical surface states and vortex-induced Majorana bound states. Here, we review superconductivity in iron chalcogenide superconductors, including bulk FeSe, doped bulk FeSe, FeTe1−xSex, intercalated FeSe materials, and monolayer FeSe and FeTe1−xSex on SrTiO3. We focus on the superconducting properties, including a survey of the relevant experimental studies, and a discussion of the different proposed theoretical pairing scenarios. In the last part of the paper, we review the growing recent evidence for nontrivial topological effects in FeSe-related materials, focusing again on interesting implications for superconductivity.

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Section: Electronic Structure Of Fesesupporting

confidence: 73%

On the Remarkable Superconductivity of FeSe and Its Close Cousins

2020

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“…Considering the different superconducting behavior in Ba 1−x K x Fe 2 As 2 and LiFe 1−x V x As, we argue that the inter-orbital scattering processes between d xz/yz and d xy orbitals increase the fluctuating moment but are detrimental to superconductivity [32]. These results are consistent with the notion that intra-orbital scattering processes between hole and electron pockets, particularly those involving d yz -d yz orbital characters, are good for superconductivity in different classes of iron-based superconductors [33][34][35][36][37].…”

Section: Resultssupporting

confidence: 86%

Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs

Dai

et al. 2020

npj Quantum Mater.

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We use neutron scattering to study vanadium (hole)-doped LiFe1−xVxAs. In the undoped state, LiFeAs exhibits superconductivity at Tc = 18 K and transverse incommensurate spin excitations similar to electron overdoped iron pnictides. Upon vanadium-doping to form LiFe0.955V0.045, the transverse incommensurate spin excitations in LiFeAs transform into longitudinally elongated in a similar fashion as that of potassium (hole) doped Ba0.7K0.3Fe2As2, but with dramatically enhanced magnetic scattering and elimination of superconductivity. This is different from the suppression of the overall magnetic excitations in hole doped BaFe2As2 and the enhancement of superconductivity near optimal hole doping. These results are consistent with density function theory plus dynamic mean field theory calculations, suggesting that vanadium-doping in LiFeAs may induce an enlarged effective magnetic moment S ef f with a spin crossover ground state arising from the inter-orbital scattering of itinerant electrons.

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“…All the samples were cleaved and measured in ultrahigh vacuum with a base pressure better than 6×10 -11 mbar. To obtain photoemission signals from one single domain, piezoelectric (PZT) stacks are used to detwin the sample in-situ [19,20]. No sample deformation was observed during the sample detwinning process.…”

Section: Methodsmentioning

confidence: 99%

Anomalous spectral weight transfer in the nematic state of iron-selenide superconductor*

et al. 2020

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Nematic phase intertwines closely with high-T c superconductivity in iron-based superconductors. Its mechanism, which is closely related to the pairing mechanism of superconductivity, still remains controversial. Comprehensive characterization of how the electronic state reconstructs in the nematic phase is thus crucial. However, most experiments focus only on the reconstruction of band dispersions. Another important characteristic of electronic state, the spectral weight, has not been studied in details so far. Here, we studied the spectral weight transfer in the nematic phase of FeSe 0.9 S 0.1 using angle-resolved photoemission spectroscopy and in-situ detwinning technique. There are two elliptical electron pockets overlapping with each other orthogonally at the Brillouin zone corner. We found that, upon cooling, one electron pocket loses spectral weight and fades away, while the other electron pocket gains spectral weight and becomes pronounced. Our results show that the symmetry breaking of electronic state is manifested by not only the anisotropic band dispersion but also the band-selective modulation of spectral weight. Our observation completes our understanding of the nematic electronic state, and put strong constraints on the theoretical models. It further provide crucial clues to understand the gap anisotropy and orbital-selective pairing in ironselenide superconductors.

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Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors

Cited by 55 publications

References 62 publications

On the Remarkable Superconductivity of FeSe and Its Close Cousins

On the Remarkable Superconductivity of FeSe and Its Close Cousins

Strong local moment antiferromagnetic spin fluctuations in V-doped LiFeAs

Anomalous spectral weight transfer in the nematic state of iron-selenide superconductor*

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