Neutron Scattering Measurements of Spatially Anisotropic Magnetic Exchange Interactions in Semiconducting K0.85Fe1.54Se2 (TN=280 K)

Abstract

We use neutron scattering to study the spin excitations associated with the stripe antiferromagnetic (AFM) order in semiconducting K${}_{0.85}$Fe${}_{1.54}$Se${}_2$ ($T_N$=$280$ K). We show that the spin wave spectra can be accurately described by an effective Heisenberg Hamiltonian with highly anisotropic in-plane couplings at $T$= $5$ K. At high temperature ($T$= $300$ K) above $T_N$, short range magnetic correlation with anisotropic correlation lengths are observed. Our results suggest that, despite the dramatic difference in the Fermi surface topology, the in-plane anisotropic magnetic couplings are a fundamental property of the iron based compounds; this implies that their antiferromagnetism may originate from local strong correlation effects rather than weak coupling Fermi surface nesting.

5 pages, 4 figures

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Cited by in corpus (5)

• Spin waves and magnetic exchange interactions in the spin ladder compound RbFe${}_2$Se${}_3$
• Soft striped magnetic fluctuations competing with superconductivity in Fe_{1+x}Te
• Strong ferromagnetic exchange interaction in the parent state of the superconductivity in BaFe${}_2$S${}_3$
• Origin of doping-induced suppression and reemergence of magnetism in LaFeAsO${}_{1-x}$H${}_x$
• Spin Waves and Spatially Anisotropic Exchange Interactions in the $\mathrm{S}=2$ Stripe Antiferromagnet Rb${}_{0.8}$Fe${}_{1.5}$S${}_2$