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Wang W, Song Y, Cao C, Tseng KF, Keller T, Li Y, Harriger LW, Tian W, Chi S, Yu R, Nevidomskyy AH, Dai P. Local orthorhombic lattice distortions in the paramagnetic tetragonal phase of superconducting NaFe 1-xNi xAs. Nat Commun 2018; 9:3128. [PMID: 30087342 PMCID: PMC6081486 DOI: 10.1038/s41467-018-05529-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 07/13/2018] [Indexed: 11/08/2022] Open
Abstract
Understanding the interplay between nematicity, magnetism and superconductivity is pivotal for elucidating the physics of iron-based superconductors. Here we use neutron scattering to probe magnetic and nematic orders throughout the phase diagram of NaFe1-xNixAs, finding that while both static antiferromagnetic and nematic orders compete with superconductivity, the onset temperatures for these two orders remain well separated approaching the putative quantum critical points. We uncover local orthorhombic distortions that persist well above the tetragonal-to-orthorhombic structural transition temperature Ts in underdoped samples and extend well into the overdoped regime that exhibits neither magnetic nor structural phase transitions. These unexpected local orthorhombic distortions display Curie-Weiss temperature dependence and become suppressed below the superconducting transition temperature Tc, suggesting that they result from the large nematic susceptibility near optimal superconductivity. Our results account for observations of rotational symmetry breaking above Ts, and attest to the presence of significant nematic fluctuations near optimal superconductivity.
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Affiliation(s)
- Weiyi Wang
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Yu Song
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Chongde Cao
- Department of Applied Physics, Northwestern Polytechnical University, Xian, 710072, China.
| | - Kuo-Feng Tseng
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
- Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - Thomas Keller
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
- Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - Yu Li
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - L W Harriger
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Wei Tian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Rong Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | | | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.
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Classen L, Xing RQ, Khodas M, Chubukov AV. Interplay between Magnetism, Superconductivity, and Orbital Order in 5-Pocket Model for Iron-Based Superconductors: Parquet Renormalization Group Study. PHYSICAL REVIEW LETTERS 2017; 118:037001. [PMID: 28157340 DOI: 10.1103/physrevlett.118.037001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Indexed: 06/06/2023]
Abstract
We report the results of the parquet renormalization group (RG) analysis of the phase diagram of the most general 5-pocket model for Fe-based superconductors. We use as an input the orbital structure of excitations near the five pockets made out of d_{xz}, d_{yz}, and d_{xy} orbitals and argue that there are 40 different interactions between low-energy fermions in the orbital basis. All interactions flow under the RG, as one progressively integrates out fermions with higher energies. We find that the low-energy behavior is amazingly simple, despite the large number of interactions. Namely, at low energies the full 5-pocket model effectively reduces either to a 3-pocket model made of one d_{xy} hole pocket and two electron pockets or a 4-pocket model made of two d_{xz}/d_{yz} hole pockets and two electron pockets. The leading instability in the effective 4-pocket model is a spontaneous orbital (nematic) order, followed by s^{+-} superconductivity. In the effective 3-pocket model, orbital fluctuations are weaker, and the system develops either s^{+-} superconductivity or a stripe spin-density wave. In the latter case, nematicity is induced by composite spin fluctuations.
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Affiliation(s)
- Laura Classen
- Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Rui-Qi Xing
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Maxim Khodas
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
| | - Andrey V Chubukov
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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