Ferromagnetic inter-layer coupling in FeSe${}_{1-x}$S${}_x$ superconductors revealed by inelastic neutron scattering

Abstract

FeSe${}_{1-x}$S${}_x$ superconductors are commonly considered layered van der Waals materials with negligible inter-layer coupling. Here, using inelastic neutron scattering to study spin excitations in single-crystal samples, we reveal that the magnetic coupling between adjacent Fe layers is not only significant, as it affects excitations up to \textcolor{black}{15} meV, but also ferromagnetic in nature, making the system different from most unconventional superconductors including iron pnictides. Our observation provides a new standpoint to understand the absence of magnetic order in FeSe${}_{1-x}$S${}_x$. Since intercalating between the Fe layers is known to enhance superconductivity and suppress the inter-layer coupling, superconductivity appears to be a more robust phenomenon in the two-dimensional limit than antiferromagnetic order.

References in corpus (21)

• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Structure determination and coexistence of superconductivity and antiferromagnetic order in (Li0.8Fe0.2)OHFeSe
• Orbital-driven nematicity in FeSe
• Spin resonance in the d-wave superconductor CeCoIn5
• Spin Gap and Resonance at the Nesting Wavevector in Superconducting FeSe0.4Te0.6
• Three-dimensional Resonance in superconducting BaFe${}_{1.9}$Ni${}_{0.1}$As${}_2$
• The origin of nematic order in FeSe
• Synthesis of a new alkali metal-organic solvent intercalated iron selenide superconductor with Tc{\approx}45K
• Resonant magnetic excitations at high energy in superconducting $\mathbf{YB}{\mathbf{a}}_2\mathbf{C}{\mathbf{u}}_3{\mathbf{O}}_{6.85}$
• Spin waves in the $(\pi ,0)$ magnetically ordered iron chalcogenide Fe${}_{1.05}$Te
• Tuning phase transitions of FeSe thin flakes by field effect transistor with solid ion conductor as gate dielectric
• Superconductivity and phase instability of NH3-free Na-intercalated FeSe1-zSz
• Anisotropic spin fluctuations in detwinned FeSe
• Two resonant magnetic modes in an overdoped high-${\mathbf{T}}_{\mathbf{c}}$ superconductor
• Dispersion of the superconducting spin resonance in underdoped and antiferromagnetic Ba(Fe1-xCox)2As2
• Low-energy spin excitations in Li(0.8)Fe(0.2)ODFeSe superconductor studied with inelastic neutron scattering
• Magnonlike dispersion of spin resonance in Ni-doped BaFe${}_2$As${}_2$
• Spin excitations in optimally P-doped BaFe2(As0.7P0.3)2superconductor
• Frustrated magnetic interactions in FeSe
• Low-energy spin excitations in optimally doped CaFe${}_{0.88}$Co${}_{0.12}$AsF superconductor studied with inelastic neutron scattering

Cited by in corpus (2)

• Quasiparticle interaction originating from Bogoliubov Fermi Surfaces under pressure in 18%-S substituted FeSe studied via NMR
• Three-dimensional spin susceptibility in Ba${}_{0.75}$K${}_{0.25}$Fe${}_2$As${}_2$: Out-of-plane modulation revealed by neutron spectroscopy and theoretical modeling