Dynamical susceptibility of a near-critical nonconserved order parameter and quadrupole Raman response in Fe-based superconductors
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PhysRevB.98.041101.pdf
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Author(s)
Klein, Avraham
Lederer, Samuel
Chowdhury, Debanjan
Berg, Erez
Chubukov, Andrey
Date Issued
July 2018
Journal
Physical Review B
Publisher
American Physical Society
Citation
Klein, Avraham et al. "Dynamical susceptibility of a near-critical nonconserved order parameter and quadrupole Raman response in Fe-based superconductors." Physical Review B 98, 4 (July 2018): 041101(R) © 2018 American Physical Society
Version
Final published version
Abstract
We analyze the dynamical response of a two-dimensional system of itinerant fermions coupled to a scalar boson ϕ, which undergoes a continuous transition towards nematic order with a d-wave form factor. We consider two cases: (a) when ϕ is a soft collective mode of fermions near a Pomeranchuk instability, and (b) when it is an independent critical degree of freedom, such as a composite spin order parameter. In both cases, the order parameter is not a conserved quantity and the d-wave fermionic polarization Π(q,Ω) remains finite even at q=0. The polarization Π(0,Ω) has similar behavior in the two cases, but the relations between Π(0,Ω) and the bosonic susceptibility χ(0,Ω) are different, leading to different forms of χ′′(0,Ω), as measured by Raman scattering. We compare our results with polarization-resolved Raman data for the Fe-based superconductors FeSe[subscript 1−x]S[subscript x],NaFe[subscript 1−x]Co[subscript x]As, and BaFe₂As₂.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.98.041101
