Temperature dependence of the paramagnetic spin excitations in BaFe$_2$As$_2$

Leland W. Harriger; Mengshu Liu; Huiqian Luo; R. A. Ewings; C. D. Frost; T. G. Perring; Pengcheng Dai

doi:10.1103/PhysRevB.86.140403

paper

Temperature dependence of the paramagnetic spin excitations in BaFe $_{2}$ As $_{2}$

arXiv:1209.6271 · doi:10.1103/PhysRevB.86.140403

Abstract

We use inelastic neutron scattering to study temperature dependence of the paramagnetic spin excitations in iron pnictide BaFe $_{2}$ As $_{2}$ throughout the Brillouin zone. In contrast to a conventional local moment Heisenberg system, where paramagnetic spin excitations are expected to have a Lorentzian function centered at zero energy transfer, the high-energy ( $ℏ ω > 100$ meV) paramagnetic spin excitations in BaFe $_{2}$ As $_{2}$ exhibit spin-wave-like features up to at least 290 K ( $T = 2.1 T_{N}$ ). Furthermore, we find that the sizes of the fluctuating magnetic moments $< m^{2} >\approx 3.6 μ_{B}^{2}$ per Fe are essentially temperature independent from the AF ordered state at $0.05 T_{N}$ to $2.1 T_{N}$ , which differs considerably from the temperature dependent fluctuating moment observed in the iron chalcogenide Fe $_{1.1}$ Te [I. A. Zaliznyak {\it et al.}, Phys. Rev. Lett. {\bf 107}, 216403 (2011).]. These results suggest unconventional magnetism and strong electron correlation effects in BaFe $_{2}$ As $_{2}$ .

5 pages, 5 figures

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Temperature dependence of the paramagnetic spin excitations in BaFe2​As2​

Abstract

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Temperature dependence of the paramagnetic spin excitations in BaFe $_{2}$ As $_{2}$