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Nematic superconductivity in LiFeAs

DOI: 10.1103/PhysRevB.102.184502 DOI Help

Authors: Y. S. Kushnirenko (IFW Dresden) , D. V. Evtushynsky (IFW Dresden; Ecole Polytechnique Federale Lausanne) , T. K. Kim (Diamond Light Source) , I. Morozov (IFW Dresden; Lomonosov Moscow State University) , L. Harnagea (IFW Dresden; Indian Institute of Science Education and Research) , S. Wurmehl (IFW Dresden) , S. Aswartham (IFW Dresden) , B. Büchner (IFW Dresden; TU Dresden) , A. V. Chubukov (University of Minnesota Twin Cities) , S. V. Borisenko (IFW Dresden)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 102

State: Published (Approved)
Published: November 2020
Diamond Proposal Number(s): 5008 , 9689

Abstract: The role of nematic order for the mechanism of high-temperature superconductivity is highly debated. In most iron-based superconductors (IBSs) the tetragonal symmetry is broken already in the normal state, resulting in orthorhombic lattice distortions, static stripe magnetic order, or both. Superconductivity then emerges, at least at weak doping, already from the state with broken C 4 rotational symmetry. One of the few stoichiometric IBSs, lithium iron arsenide superconducts below 18 K and does not display either structural or magnetic transition in the normal state. Here we demonstrate, using angle-resolved photoemission spectroscopy, that even the superconducting state in LiFeAs is also a nematic one. We observe spontaneous breaking of the rotational symmetry in the gap amplitude on all Fermi surfaces, as well as unidirectional distortion of the Fermi pockets. Remarkably, these deformations are hardly visible above superconducting T c . Our results demonstrate the realization of the phenomenon of superconductivity-induced nematicity in IBSs, emphasizing the intimate relation between them. We suggest a theoretical explanation based on the emergence of a secondary instability inside the superconducting state, which leads to the nematic order and s − d mixing in the gap function.

Journal Keywords: Electronic structure; Multiband superconductivity; Iron-based superconductors; Angle-resolved photoemission spectroscopy

Subject Areas: Physics, Materials

Instruments: I05-ARPES

Other Facilities: BESSY II

Added On: 09/11/2020 11:52

Discipline Tags:

Superconductors Quantum Materials Hard condensed matter - electronic properties Physics Materials Science

Technical Tags:

Spectroscopy Angle Resolved Photoemission Spectroscopy (ARPES)