Doping dependence of the Nernst effect in Eu(Fe1-xCox)2As2 - departure from Dirac fermions physics

TL;DR

This study investigates how cobalt doping affects the transport properties and Nernst effect in Eu(Fe1-xCox)2As2, revealing a transition from Dirac fermion behavior to a conventional metallic state with doping.

Contribution

It provides the first systematic analysis of doping-dependent transport and Nernst effect in Eu(Fe1-xCox)2As2, highlighting departure from Dirac fermion physics with cobalt doping.

Findings

Parent compound described by Dirac fermions model

Cobalt doping induces a transition to metallic behavior

Eu2+ antiferromagnetic order has minor impact

Abstract

We report a systematic study of the transport properties in the series of Eu(Fe1-xCox)2As2 single crystals with x = 0, 0.15, 0.20 and 0.30. Spin-density-wave order is observed in the undoped and the least doped samples (x = 0, 0.15), while for x = 0.15 and 0.20 Eu(Fe1-xCox)2As2 becomes a superconductor. We found the properties of the parent EuFe2As2 compound well described by the Dirac fermions model, whereas cobalt doping caused an evolution of the system toward a regular metallic state. The antiferromagnetic ordering of the Eu2+ ions at T_N ~ 20 K has only minor influence on the measured quantities.