Magnetotransport in La(Fe,Ru)AsO as a probe of band structure and mobility

In this paper, we investigate the Ru-substituted LaFeAsO compound by studying the magnetotransport behavior and its relationship with the band structure in different regimes of temperature, magnetic field, and Ru content. In particular, we analyze the magnetoresistance of LaFe${}_{1\ensuremath{-}x}$Ru${}_{x}$AsO (0 \ensuremath{\le} $x$ \ensuremath{\le} 0.6) samples with the support of ab initio calculations, and we find that in the whole series: (i) the transport is dominated by electron bands only; (ii) the magnetoresistance exhibits distinctive features related to the presence of Dirac cones; indeed, ab initio calculations confirm the presence of anisotropic Dirac cones in the band structure; (iii) the low temperature mobility is exceptionally high and reaches 18.6 m${}^{2}$/(Vs) in the Ru-free sample at $T$ = 2 K in the extreme limit of a single Landau level occupied in the Dirac cones; (iv) the mobility drops abruptly above 10--15 K; (v) the disorder has a very weak effect on the band mobilities and on the transport properties; and (vi) there exists a correlation between the temperature ranges of Dirac cones and SDW carrier condensation. These findings evidence the outstanding transport properties of Dirac cones in Fe-based pnictides parent compounds.