Transition metal doping of FeSeTe: what can we learn from transport properties

Abstract

During recent years, many studies have been devoted to probing superconductivity in the iron-based superconductors via impurity doping. Doping is a powerful tool used for tuning of material parameters: it may modify the density of carriers, the magnetic fluctuations, or the scattering rates. Many of these effects stem from the modifications of the Fermi surface topology. In this paper, after a brief general introduction on the transport in doped iron superconductors, we discuss the recent transport investigations of the transition metal-doped iron–chalcogenide crystals, . So far, very few attempts of successful doping have been described for this material. We show that the evolution of the resistivity and the Hall effect up to high doping levels suggests that Co-doped undergoes the changes consistent with electron doping. On the other hand, in case of Ni impurity some additional pair breaking is inferred.

Keywords:

• iron-based superconductors
• impurities
• transport properties
• single crystals
• Hall effect

Acknowledgements

This work has been done in collaboration with D. J. Gawryluk, A. Malinowski, and M. Berkowski. We would like to thank M. Kozłowski for experimental support.

Notes

1 The measurements of magnetic properties of the doped crystals, performed recently, show neither localized magnetic moment, nor any magnetic order developing as a result of doping. This indicates that the low-T reduction of the resistivity and Hall coefficient are electronic in origin. As described in detail in Ref. [26], the analysis based on two band model suggests that these effects reflect the evolution of the hole and electron pockets induced by impurity doping, while strong electron localization most likely contributes to fast suppression of superconductivity by the Ni impurity.

Additional information

Funding

This work was partially supported by the EC through the FunDMS Advanced Grant of the European Research Council (FP7 Ideas) and by the National Science Centre (Poland) [grant number 2011/01/B/ST3/00462]. This research was partially performed in the NanoFun laboratories co-financed by the European Regional Development Fund [grant number POIG.02.02.00-00-025/09].