Damped spin-wave excitations in the itinerant antiferromagnet $\gamma$-Fe${}_{0.7}$Mn${}_{0.3}$

Abstract

The collective spin-wave excitations in the antiferromagnetic state of $\gamma$-Fe${}_{0.7}$Mn${}_{0.3}$ were investigated using the inelastic neutron scattering technique. The spin excitations remain isotropic up to the high excitation energy, $\hslash \omega =78$ meV. The excitations gradually become broad and damped above 40 meV. The damping parameter $\gamma$ reaches 110(16) meV at $\hslash \omega =78$ meV, which is much larger than that for other metallic compounds, e.g., CaFe${}_2$As${}_2$ (24 meV), La${}_{2-2x}$Sr${}_{1+2x}$Mn${}_2$O${}_7$ ($52-72$ meV), and Mn${}_{90}$Cu${}_{10}$ (88 meV). In addition, the spin-wave dispersion shows a deviation from the relation $(\hslash \omega {)}^2=c^2{q}^2+{\Delta }^2$ above 40 meV. The group velocity above this energy increases to 470(40) meVÅ, which is higher than that at the low energies, $c=226(5)$ meVÅ. These results could suggest that the spin-wave excitations merge with the continuum of the individual particle-hole excitations at 40 meV.

arXiv comment7 pages, 6 figures

References in corpus (19)

• Unconventional sign-reversing superconductivity in LaFeAsO_(1-x)F_x
• Anomalous Hall Effect and Magnetic Monopoles in Momentum-Space
• Theory of Electron Nematic Order in LaOFeAs
• Spin Waves and Magnetic Exchange Interactions in CaFe2As2
• Orbital ferromagnetism and anomalous Hall effect in antiferromagnets on distorted fcc lattice
• Magnetism and Charge Dynamics in Iron Pnictides
• Orbital Order and Spontaneous Orthorhombicity in Iron Pnictides
• Nematic spin fluid in the tetragonal phase of BaFe2As2
• Itinerant magnetic excitations in antiferromagnetic CaFe2As2
• Theory of itinerant magnetic excitations in the SDW phase of iron-based superconductors
• The magnetic excitation spectra in BaFe${}_2$As${}_2$: a two-particle approach within DFT+DMFT
• Itinerant Spin Excitations in SrFe2As2 Measured by Inelastic Neutron Scattering
• Spin and Charge Dynamics Ruled by Antiferromagnetic Order in Iron Pnictides
• Spectacular doping dependence of interlayer exchange and other results on spin waves in bilayer manganites
• The strongly enhanced magnetic excitations near the quantum critical point of Cr${}_{1-x}$V${}_x$ and why strong exchange enhancement need not imply heavy fermion behavior
• Magnetic order without tetragonal-symmetry-breaking in iron arsenides: microscopic mechanism and spin-wave spectrum
• Spin excitations in the nematic phase and the metallic stripe spin-density wave phase of iron pnictides
• Collective magnetic excitations of $C_4$ symmetric magnetic states in iron-based superconductors
• Spin Dynamics and Resonant Inelastic X-ray Scattering in Chromium with Commensurate Spin-Density Wave Order

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