Spin dynamics of aJ1-J2-Kmodel for the paramagnetic phase of iron pnictides

2011/12/31 by Rong Yu, Zhentao Wang, Pallab Goswami +4
Materials Science · Physics and Astronomy · #Antiferromagnetism #Condensed matter physics #Inelastic neutron scattering #Iron-based superconductors research #Neutron scattering #Paramagnetism #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Rare-earth and actinide compounds #Scattering #Spin (aerodynamics) #Thermodynamics #cond-mat.str-el #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevb.86.085148

published as Phys. Rev. B 86, 085148 (2012) · 13 pages, 11 figures, to be published in Phys. Rev. B

arxiv created 2012/08/16 · openalex publication_date 2012/08/31 · arxiv updated 2012/09/03 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We study the finite-temperature spin dynamics of the paramagnetic phase of iron pnictides within an antiferromagnetic J₁-J₂ Heisenberg model on a square lattice with a biquadratic coupling \ensuremath-K(S_i\ifmmode⋅\else\textperiodcentered\fiS_j)² between the nearest-neighbor spins. Our focus is on the paramagnetic phase in the parameter regime of this J₁-J₂-K model where the ground state is a (\ensuremathπ,0) collinear antiferromagnet. We treat the biquadratic interaction via a Hubbard-Stratonovich decomposition and study the resulting effective quadratic-coupling model using both modified spin wave and Schwinger boson mean-field theories; the results for the spin dynamics derived from the two methods are very similar. We show that the spectral weight of dynamical structure factor S(q,\ensuremathω) is peaked at ellipses in the momentum space at low excitation energies. With increasing energy, the elliptic features expand towards the zone boundary and gradually split into two parts, forming a pattern around (\ensuremathπ,\ensuremathπ). Finally, the spectral weight is anisotropic, being larger along the major axis of the ellipse than along its minor axis. These characteristics of the dynamical structure factor are consistent with the recent measurements of the inelastic neutron scattering spectra of BaFe₂As₂ and SrFe₂As₂.

Citations

• Correlated Electronic Structure ofLaO1−xFxFeAs
• Band Narrowing and Mott Localization in Iron OxychalcogenidesLa2O2Fe2O(Se,S)2
• Signatures of Electronic Correlations in Optical Properties ofLaFeAsO1−xFx
• Paramagnetic spin correlations inCaFe2As2single crystals
• Theory of itinerant magnetic excitations in the spin-density-wave phase of iron-based superconductors
• Itinerant spin excitations in SrFe2As2measured by inelastic neutron scattering
• Theory of electron nematic order in LaFeAsO
• Symmetry-breaking orbital anisotropy observed for detwinned Ba(Fe 1- x Co x ) 2 As 2 above the spin density wave transition
• Orbital ordering and unfrustrated(π,0)magnetism from degenerate double exchange in the iron pnictides
• Anisotropy, Itineracy, and Magnetic Frustration in High-TCIron Pnictides
• Large-Nexpansion for frustrated quantum antiferromagnets
• Strong Correlations and Magnetic Frustration in the HighTcIron Pnictides
• Spin dynamics of aJ1−J2antiferromagnet and its implications for iron pnictides
• Origin of the 150-K Anomaly in LaFeAsO: Competing Antiferromagnetic Interactions, Frustration, and a Structural Phase Transition

Cited by

• Electron Correlation and Spin Dynamics in Iron Pnictides and Chalcogenides