Orbital-dependent Fermi surface shrinking as a fingerprint of nematicity in FeSe

We report the results of a parquet renormalization group (RG) study of competing instabilities in the full 2D four pocket, three orbital low-energy model for iron-based superconductors. We derive and analyze the RG flow of the couplings, which describe all symmetry-allowed interactions between low-energy fermions. Despite that the number of the couplings is large, we argue that there are only two stable fixed trajectories of the RG flow and one weakly unstable fixed trajectory with a single unstable direction. Each fixed trajectory has a finite basin of attraction in the space of initial system parameters. On the stable trajectories, either interactions involving only dxz and dyz or only dxy orbital components on electron pockets dominate, while on the weakly unstable trajectory interactions involving dxz (dyz) and dxy orbital states on electron pockets remain comparable. The behavior along the two stable fixed trajectories has been analyzed earlier [A.V. Chubukov, M. Khodas, and R.M. Fernandes, arXiv:1602.05503]. Here we focus on the system behavior along the weakly unstable trajectory and apply the results to FeSe. We find, based on the analysis of susceptibilities along this trajectory, that the leading instability upon lowering the temperature is towards a three-component d-wave orbital nematic order. Two components are the differences between fermionic densities on dxz and dyz orbitals on hole pockets and on electron pockets, and the third one is the difference between the densities of dxy orbitals on the two electron pockets. We argue that this order is consistent with the splitting of band degeneracies, observed in recent photoemission data on FeSe by A. Fedorov et al [arXiv:1606.03022].

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“…ARPES data for Γ 1,e /Γ 2,e from different groups [45][46][47][48] are similar but not identical. We will use recent ARPES data from Ref.…”

Section: Implications For Experimentsmentioning

confidence: 91%

Competing instabilities, orbital ordering, and splitting of band degeneracies from a parquet renormalization group analysis of a four-pocket model for iron-based superconductors: Application to FeSe

et al. 2017

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“…We note that the larger electron pocket appears much shallower in the experiment because of the stronger renormalization of the d xy band mentioned earlier. It is also clear now that the apparently elongated ellipses can be elongated already in the tetragonal phase, mostly because the experimental Fermi level runs close to the bottoms of the electron pockets and the nematicity123467 or the orbital dependent Fermi surface shrinking5 plays secondary role.…”

Section: Breakdown Of Tetragonal Symmetrymentioning

confidence: 94%

Effect of nematic ordering on electronic structure of FeSe

Fedorov

Yaresko

Kim

et al. 2016

Sci Rep

135

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Electronically driven nematic order is often considered as an essential ingredient of high-temperature superconductivity. Its elusive nature in iron-based superconductors resulted in a controversy not only as regards its origin but also as to the degree of its influence on the electronic structure even in the simplest representative material FeSe. Here we utilized angle-resolved photoemission spectroscopy and density functional theory calculations to study the influence of the nematic order on the electronic structure of FeSe and determine its exact energy and momentum scales. Our results strongly suggest that the nematicity in FeSe is electronically driven, we resolve the recent controversy and provide the necessary quantitative experimental basis for a successful theory of superconductivity in iron-based materials which takes into account both, spin-orbit interaction and electronic nematicity.

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“…It has been argued that orbital and not spin degrees of freedom are the driving force behind nematic ordering in FeSe [2,7], although perspectives that emphasise the role of magnetic fluctuations have also been suggested [8][9][10][11]. The desire to determine the magnitude and momentum-dependence of orbital ordering effects has motivated several angle-resolved photo-emission spectroscopy (ARPES) studies focusing on the evolution of the electronic structure through the nematic transition [12][13][14][15][16][17][18][19]. However, a significant challenge is that FeSe samples will naturally form structural twin domains in the nematic phase, leaving some ambiguity in the interpretation of the data because both domains contribute to the measured intensity and restore fourfold symmetry macroscopically.…”

Section: Introductionmentioning

confidence: 99%

Electronic anisotropies revealed by detwinned angle-resolved photo-emission spectroscopy measurements of FeSe

et al. 2017

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We report high resolution angle-resolved photo-emission spectroscopy (ARPES) measurements of detwinned FeSe single crystals. The application of a mechanical strain is used to promote the volume fraction of one of the orthorhombic domains in the sample, which we estimate to be 80% detwinned. While the full structure of the electron pockets consisting of two crossed ellipses may be observed in the tetragonal phase at temperatures above 90K, we find that remarkably, only one peanut-shaped electron pocket oriented along the longer a axis contributes to the ARPES measurement at low temperatures in the nematic phase, with the expected pocket along b being not observed. Thus the low temperature Fermi surface of FeSe as experimentally determined by ARPES consists of one elliptical hole pocket and one orthogonally-oriented peanut-shaped electron pocket. Our measurements clarify the long-standing controversies over the interpretation of ARPES measurements of FeSe.

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Orbital-dependent Fermi surface shrinking as a fingerprint of nematicity in FeSe

Abstract: International audienc

Cited by 123 publications

References 64 publications

Competing instabilities, orbital ordering, and splitting of band degeneracies from a parquet renormalization group analysis of a four-pocket model for iron-based superconductors: Application to FeSe

Competing instabilities, orbital ordering, and splitting of band degeneracies from a parquet renormalization group analysis of a four-pocket model for iron-based superconductors: Application to FeSe

Effect of nematic ordering on electronic structure of FeSe

Electronic anisotropies revealed by detwinned angle-resolved photo-emission spectroscopy measurements of FeSe

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