Abstract
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.
Highlights
Electronic nematicity, defined as the breaking of the fourfold rotational symmetry by the electronic degree of freedom (d.o.f.), is widely found in iron-based superconductor (FeSC) families [1,2,3]
We present high-quality angleresolved photoemission spectroscopy (ARPES) measurements of the electronic structure of completely detwinned FeSe
Our data unambiguously demonstrate a nematic energy splitting of 50 meV at the BZ corner between the dxz and dyz orbitals, consistent with other FeSCs where the nematic order is strongly coupled to a magnetic order
Summary
Electronic nematicity, defined as the breaking of the fourfold rotational symmetry by the electronic degree of freedom (d.o.f.), is widely found in iron-based superconductor (FeSC) families [1,2,3]. While the cause of the missing electron pocket remains elusive, the incorporation of its absence into theoretical models [49,50,51,52] is deemed necessary to reproduce the observed strongly anisotropic superconducting gap [41,45,49] To clarify these issues, we present high-quality angleresolved photoemission spectroscopy (ARPES) measurements of the electronic structure of completely detwinned FeSe. Our data unambiguously demonstrate a nematic energy splitting of 50 meV at the BZ corner between the dxz and dyz orbitals, consistent with other FeSCs where the nematic order is strongly coupled to a magnetic order. Our results provide the basis for future theoretical models of FeSe
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