Coexistence of Dirac-cone states and superconductivity in iron pnictide Ba(Fe1−xRuxAs)2

Abstract

The Ru doping effect on the Dirac-cone states is investigated in iron pnictide superconductors Ba(Fe${}_{1\ensuremath{-}x}$Ru${}_{x}$As)${}_{2}$ using transverse magnetoresistance (${R}_{\mathrm{M}}$) measurements as a function of temperature. The linear development of ${R}_{\mathrm{M}}$ against magnetic field $B$ is observed for $x=0$--0.244 at low temperatures below the antiferromagnetic transition. The $B$-linear ${R}_{\mathrm{M}}$ is interpreted in terms of the quantum limit of the Dirac-cone states by using the model proposed by Abrikosov. An intriguing evidence is shown that the Dirac-cone state persists on the electronic phase diagram where antiferromagnetism and superconductivity coexist.