Effects of the magnetic orderings on the dynamical conductivity: optical investigations of EuFe${}_2$As${}_2$ single crystals

Abstract

The magnetic, transport and optical properties of EuFe${}_2$As${}_2$ single crystals have been investigated parallel and perpendicular to the $ab$-plane. The anisotropy ${\rho }_c/{\rho }_{ab}\approx 8$ depends only slightly on temperature. In both orientations, the spin-density wave transition at $T_{\mathrm{SDW}}=189$ K shows up as a considerable increase in the dc resistivity. Susceptibility measurements evidence the magnetic order of the Eu${}^{2+}$ moments at $T_N=19$ K with little influence on the electronic transport taking place in the FeAs layers. Polarization-dependent infrared spectroscopy reveals strongly anisotropic optical properties and yields a carrier density of only $4.2\times 10^{21}{\mathrm{cm}}^{-3}$ and a bandmass of $m_b=2m_0$. A sizeable Drude contribution is present at all temperatures and narrows upon cooling. Below $T_{\mathrm{SDW}}$, the spin-density-wave gap develops in the in-plane optical conductivity; no appreciable change is detected for the perpendicular polarization. Modifications in the phonon features are associated with changes of the electronic properties at $T_{\mathrm{SDW}}$. The extended Drude analysis yields a linear behavior of the frequency-dependent scattering rate below $T_{\mathrm{SDW}}$, indicating an interaction between the charge carriers and spin fluctuations in the spin-density-wave state.

10 pages, 8 figures

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Cited by in corpus (9)

• Electrodynamics of Correlated Electron Materials
• Evolution of the optical spectrum with doping in iron pnictides Ba(Fe1-xCox)2As2
• Electrodynamics of electron doped iron-pnictide superconductors: Normal state properties
• Optical properties of the iron-arsenic superconductor BaFe1.85Co0.15As2
• Phonon anomalies in pure and underdoped R{1-x}K{x}Fe{2}As{2} (R = Ba, Sr) investigated by Raman light scattering
• Magnetic ordering and dense Kondo behaviour in EuFe${}_2$P${}_2$
• Analysis of spin density wave conductivity spectra of iron pnictides in the framework of density functional theory
• Phonon splitting and anomalous enhancement of infrared-active modes in BaFe${}_2$As${}_2$
• Optical properties of the iron-chalcogenide superconductor FeTe0.55Se0.45