Nernst effect in single crystals of the pnictide superconductor CaFe1.92Co0.08As2 and parent compound CaFe2As2

TL;DR

This study investigates the Nernst effect, Hall effect, and thermoelectric power in CaFe2As2 and Co-doped CaFe1.92Co0.08As2 single crystals, revealing differences related to spin-density-wave order and superconductivity.

Contribution

It provides new insights into how doping affects the Nernst response and related electronic properties in pnictide superconductors.

Findings

Enhanced Nernst coefficient in both samples due to quasiparticle flow

Rapid rise of Nernst coefficient in CaFe2As2 at SDW transition

No significant Nernst response near superconducting transition in Co-doped sample

Abstract

We report a combined study of the Nernst coefficient (v), Hall effect and thermoelectric power of CaFe2As2 and CaFe1.92Co0.08As2 single crystals. The absolute value of v in both samples is enhanced, probably due to ambipolar flow of electron- and hole-like quasiparticles. The onset of spin-density-wave order in CaFe2As2 causes further rapid rise of the Nernst coefficient. On the contrary, in the CaFe1.92Co0.08As2 crystal we do not see any feature of v(T), which could be clearly associated with SDW fluctuations. In this Co-doped sample there is also no noticeable increase in of v in the vicinity of superconducting transition, despite the expectation of such due to vortex movement.