Different effects of Ni and Co substitution on the transport properties of BaFe2As2

TL;DR

This study compares how Ni and Co substitutions affect the electrical transport in BaFe2As2, revealing differences in hole contribution and scattering effects despite similar phase diagrams.

Contribution

It provides a detailed comparison of Ni and Co doping effects on transport properties using resistivity and Hall measurements within a two-band model framework.

Findings

Hole contribution is more significant in Ni-doped samples.

Ni acts as a stronger scatterer for electrons than Co.

Transport properties differ despite similar phase diagrams.

Abstract

We report resistivity and Hall effect results on Ba(Fe1-xNix)2As2 and compare them with those in Ba(Fe1-xCox)2As2. The Hall number RH is negative for all x values from 0.01 to 0.14, which indicates that electron carriers dominate the transport both in the magnetic and paramagnetic regime. We analyse the data in the framework of a two-band model. Without any assumption on the number of carriers, we show that the electron resistivity can be estimated with good accuracy in the low temperature paramagnetic range. Although the phase diagrams of the two families are very similar with respect to the extra electrons added in the system, we find that the transport properties differ in several aspects. First, we evidence that the contribution of holes to the transport is more important for Ni doping than for Co doping. Secondly, Ni behaves as a stronger scatterer for the electrons, as the increase of the residual electron resistivity rho/x is about four times larger for Ni than for Co in the most doped samples.