Giant biquadratic interaction induced magnetic anisotropy in the iron-based superconductor AxFe2-ySe2

Abstract

The emergence of the electron-pocket only iron-based superconductor AxFe2-ySe2 (A = alkali metal) challenges the Fermi-surface nesting picture established in iron-pnictides. It was widely believed that magnetism is correlated with the superconductivity in AxFe2-ySe2. Unfortunately, the highly anisotropic exchange parameters and the disagreement between theoretical calculations and experimental results triggered a fierce debate on the nature of magnetism in AxFe2-ySe2. Here we find that the strong magnetic anisotropy is from the anisotropic biquadratic interaction. In order to accurately obtain the magnetic interaction parameters, we propose a universal method, which does not need including other high energy configurations as did in conventional energy mapping method. We show that our model successfully captures the magnetic interactions in AxFe2-ySe2 and correctly predicts the spin wave spectrum, in quantitative agreement with the experimental observation. These results suggest that the local moment picture, including the biquadratic term, can describe accurately the magnetic properties and spin excitations in AxFe2-ySe2, which sheds new light on the future study of the high-Tc iron-based superconductors.

3 figures to appear in prb

References in corpus (10)

• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Theory of Electron Nematic Order in LaOFeAs
• Magnetism and its microscopic origin in iron-based high-temperature superconductors
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Fe-based high temperature superconductivity with Tc=31K bordering an insulating antiferromagnet in (Tl,K)FexSe2 Crystals
• Spin-orbital frustrations and anomalous metallic state in iron-pnictide superconductors
• Effect of magnetic frustration on nematicity and superconductivity in Fe chalcogenides
• Antiferromagnetic ground state with pair-checkboard order in FeSe
• Neutron Scattering Measurements of Spatially Anisotropic Magnetic Exchange Interactions in Semiconducting K0.85Fe1.54Se2 (TN=280 K)
• Spin excitations in K${}_2$Fe${}_{4+x}$Se${}_5$: linear response approach

Cited by in corpus (6)

• Higher-order exchange interactions in two-dimensional magnets
• Quantum rescaling, domain metastability and hybrid domain-walls in two-dimensional CrI3 magnets
• Possible Nematic Spin Liquid in Spin-$1$ Antiferromagnetic System on the Square Lattice: Implication for the Nematic Paramagnetic State of FeSe
• Quantum phase diagram of spin-$1$ $J_1-J_2$ Heisenberg model on the square lattice: an infinite projected entangled-pair state and density matrix renormalization group study
• The role of interstitial hydrogen in SrCoO${}_{2.5}$ antiferromagnetic insulator
• Electronic and spin dynamics in the insulating iron pnictide NaFe${}_{0.5}$Cu${}_{0.5}$As