Unified Spin Model for Magnetic Excitations in Iron Chalcogenides

Abstract

Recent inelastic neutron scattering (INS) measurements on FeSe and Fe(Te${}_{1-x}$Se${}_x$), have sparked intense debate over the nature of the ground state in these materials. Here we propose an effective bilinear-biquadratic spin model which is shown to consistently describe the evolution of low-energy spin excitations in FeSe, both under applied pressure and upon Se/Te substitution. The phase diagram, studied using a combination of variational mean-field, flavor-wave calculations, and density-matrix renormalization group (DMRG), exhibits a sequence of transitions between the columnar antiferromagnet common to the iron pnictides, the non-magnetic ferroquadrupolar phase attributed to FeSe, and the double-stripe antiferromagnetic order known to exist in Fe${}_{1+y}$Te. The calculated spin structure factor in these phases mimics closely that observed with INS in the Fe(Te${}_{1-x}$Se${}_x$), series. In addition to the experimentally established phases, the possibility of incommensurate magnetic order is also predicted.

9 pages, 10 figures in the main text; plus 5 pages of supplementary materials

References in corpus (27)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)
• Theory of Electron Nematic Order in LaOFeAs
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• First-order magnetic and structural phase transitions in Fe${}_{1+y}$Se${}_x$Te${}_{1-x}$
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Pairing Symmetry in a Two-Orbital Exchange Coupling Model of Oxypnictides
• Magnetism in Fe-based superconductors
• The quadrupolar phases of the S=1 bilinear-biquadratic Heisenberg model on the triangular lattice
• From (pi, 0) magnetic order to superconductivity with (pi, pi) magnetic resonance in Fe1.02(Te1-xSex)
• Spin Gap and Resonance at the Nesting Wavevector in Superconducting FeSe0.4Te0.6
• Orbital-selective Mott Phase in Multiorbital Models for Alkaline Iron Selenides K(1-x)Fe(2-y)Se2
• Strong cooperative coupling of pressure-induced magnetic order and nematicity in FeSe
• U(1) Slave-spin theory and its application to Mott transition in a multi-orbital model for iron pnictides
• Strong $(\pi ,0)$ spin fluctuations in $\beta$-FeSe observed by neutron spectroscopy
• Pressure-induced antiferromagnetic transition and phase diagram in FeSe
• Spin waves in the $(\pi ,0)$ magnetically ordered iron chalcogenide Fe${}_{1.05}$Te
• Pressure Induced Stripe-order Antiferromagnetism and First-order Phase Transition in FeSe
• Theory for Superconductivity in Iron Pnictides at Large Coulomb U Limit
• Orbital differentiation and the role of orbital ordering in the magnetic state of Fe superconductors
• Short-range incommensurate magnetic order near the superconducting phase boundary in Fe(1+d)Te(1-x)Se(x)
• Spin Ferroquadrupolar Order in the Nematic Phase of FeSe
• Antiferroquadrupolar order and rotational symmetry breaking in a generalized bilinear-biquadratic model on a square lattice
• Thermal evolution of antiferromagnetic correlations and tetrahedral bond angles in superconducting FeTe${}_{1-x}$Se${}_x$
• Magnetic hour-glass dispersion and its relation to high-temperature superconductivity in iron-tuned Fe${}_{1+y}$Te${}_{0.7}$Se${}_{0.3}$
• Low energy magnetic excitations from the Fe${}_{1+y-z}$(Ni/Cu)${}_z$Te${}_{1-x}$Se${}_x$ system
• Magnetic neutron scattering studies on the Fe-based superconductor system Fe${}_{1+y}$Te${}_{1-x}$Se${}_x$