Optical study on the spin-density wave properties in single crystalline Na${}_{1-\delta }$FeAs

Abstract

We report an optical investigation on the in-plane charge dynamics for Na${}_{1-\delta }$FeAs single crystal. A clear optical evidence for the spin-density wave (SDW) gap is observed. As the structural/magnetic transitions are separated in the Na${}_{1-\delta }$FeAs case, we find the SDW gap opens in accordance with the magnetic transition. Comparing with the optical response of other FeAs-based parent compounds, both the gap value 2$\Delta$ and the energy scale for the gap-induced spectral weight redistribution are smaller in Na${}_{1-\delta }$FeAs. Our findings support the itinerant origin of the antiferromagnetic transition in the FeAs-based system.

5 figures, 5 pages