Multi-band model analysis of transport properties of Ba(FeAs)$_2$

In iron pnitides, unique energetic band topology and interband antiferromagnetic scatterings are the main sources of rich physics, including multiband superconductivity and Dirac cones quantum states [1, 2]. Despite its importance, the band structure of iron pnictides is not fully understood, especially in terms of transport phenomena. In this meeting, we present that the tranport properties of Ba(FeAs)$_2$, a typical iron pnictide compound, are strongly affected by the shape of Fermi surfaces and the high mobility ($\mu$) in the Dirac cones. From magnetic-field ($B$) dependencies of the conductivity tensor under $B < 50$ T, we successfully extracted a spectrum of carrier number as a function of $\mu$. Whereas the hole side of the spectra is purely characterized by parabolic hole pockets, the electron side shows interesting effects originating from partly concave Fermi pockets as well as the very high $\mu$ (50,000 cm$^2$V$^{-1}$s$^{-1}$) of the Dirac carriers. Our observations are also in a good agreement with the first principles band calculations and experimental spectroscopic observations on its Fermi surface [3, 4]. [1] K. Kuroki et al, PRL 101 (2008) [2] Ran et al, PRB 79 (2009) [3] Yin et al, Nat.Phys. 7 (2011) [4] T. Shimojima, PRL 104 (2010)