Spin fluctuations in the ultranodal superconducting state of Fe(Se,S)

Abstract

The iron-based superconductor FeSe isovalently substituted with S displays an abundance of remarkable phenomena that have not been fully understood, at the center of which are apparent zero-energy excitations in the superconducting state in the tetragonal phase. The phenomenology has been generally consistent with the proposal of the so-called ultranodal states where Bogoliubov Fermi surfaces are present. Recently, nuclear magnetic resonance measurements have seen unusually large upturns in the relaxation rate as temperature decreases to nearly zero in these systems, calling for theoretical investigations. In this paper, we calculate the spin susceptibility of an ultranodal superconductor including correlation effects within the random phase approximation. Although the non-interacting mean-field calculation rarely gives an upturn in the low temperature relaxation rate within our model, we found that correlation strongly enhances scattering between coherent parts of the Bogoliubov Fermi surface, resulting in robust upturns when the interaction is strong. Our results suggest that in addition to the presence of Bogoliubov Fermi surfaces, correlation and multiband physics also play important roles in the system's low energy excitations.

References in corpus (13)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Ironing out the details of unconventional superconductivity
• Bogoliubov Fermi surfaces in superconductors with broken time-reversal symmetry
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Pressure-induced antiferromagnetic transition and phase diagram in FeSe
• Suppression of electronic correlations by chemical pressure from FeSe to FeS
• Inflated nodes and surface states in superconducting half-Heusler compounds
• Electronic nematic states tuned by isoelectronic substitution in bulk FeSe1-xSx
• Leading superconducting instabilities in three-dimensional models for Sr2RuO4
• Impact of Nematicity on the Relationship between Antiferromagnetic Fluctuations and Superconductivity in FeSe0.91S0.09 Under Pressure
• Spin fluctuations from Bogoliubov Fermi surfaces in the superconducting state of S-substituted FeSe
• Nematic Bogoliubov Fermi surfaces from magnetic toroidal order in FeSe${}_{1-x}$S${}_x$
• Microscopic origin of ultranodal superconducting states in spin-1/2 systems

Cited by in corpus (2)

• Quasiparticle interaction originating from Bogoliubov Fermi Surfaces under pressure in 18%-S substituted FeSe studied via NMR
• Evolution and Instability of Bogoliubov Fermi Surfaces under Zeeman Field