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Emergent phases in iron pnictides: Double-Q antiferromagnetism, charge order and enhanced nematic correlations
Electron correlations produce a rich phase diagram in the iron pnictides.
Earlier theoretical studies on the correlation effect demonstrated how quantum
fluctuations weaken and concurrently suppress a -symmetric single-Q
antiferromagnetic order and a nematic order. Here we examine the emergent
phases near the quantum phase transition. For a -symmetric collinear
double-Q antiferromagnetic order, we show that it is accompanied by both a
charge order and an enhanced nematic susceptibility. Our results provide
understanding for several intriguing recent experiments in hole-doped iron
arsenides, and bring out common physics that underlies the different magnetic
phases of various iron-based superconductors.Comment: 5+6 pages, 2 figures; (v2) issues with cross-referencing between the
main text and supplementary material are fixe
The Nematic Energy Scale and the Missing Electron Pocket in FeSe
Superconductivity emerges in proximity to a nematic phase in most iron-based
superconductors. It is therefore important to understand the impact of
nematicity on the electronic structure. Orbital assignment and tracking across
the nematic phase transition prove to be challenging due to the multiband
nature of iron-based superconductors and twinning effects. Here, we report a
detailed study of the electronic structure of fully detwinned FeSe across the
nematic phase transition using angle-resolved photoemission spectroscopy. We
clearly observe a nematicity-driven band reconstruction involving dxz, dyz, and
dxy orbitals. The nematic energy scale between dxz and dyz bands reaches a
maximum of 50 meV at the Brillouin zone corner. We are also able to track the
dxz electron pocket across the nematic transition and explain its absence in
the nematic state. Our comprehensive data of the electronic structure provide
an accurate basis for theoretical models of the superconducting pairing in
FeSe
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