Importance of Fermi Surface Topology for In-Plane Resistivity Anisotropy in Hole- and Electron-Doped Ba(Fe1−xTMx)2As2 (TM = Cr, Mn, and Co)

The in-plane anisotropy of resistivity has been investigated for Ba(Fe1−xTMx)2As2 (TM-Ba122, TM = Cr, Mn, and Co) where the substitution sites are the same but the doped carriers are different for different TM elements. The Hall coefficient measurements indicated that hole carriers are effectively doped by Cr substitution but not by Mn substitution. It has been found that the resistivity difference Δρ = ρb − ρa in the antiferromagnetic-orthorhombic (AFO) phase of Cr-Ba122 is initially positive but it turns to negative with increasing Cr content, whereas the positive Δρ monotonically increases with Mn substitution in Mn-Ba122. In the paramagnetic-tetragonal phase, Δρ is always positive, but it decreases with substitution in Cr-Ba122, in contrast to the electron-doped case. These results demonstrate that the resistivity anisotropy exhibits electron–hole asymmetry in both AFO and nematic phases and that it depends on the Fermi surface topology whether the carrier scattering results in a positive or negative Δρ.