Anisotropy of the Seebeck and Nernst coefficients in parent compounds of the iron-based superconductors

Abstract

In-plane longitudinal and transverse thermoelectric phenomena in two parent compounds of iron-based superconductors are studied. Namely, the Seebeck (S) and Nernst (n) coefficients were measured in the temperature range 10 - 300 K for BaFe2As2 and CaFe2As2 single crystals that were detwinned in-situ. The thermoelectric response shows sizeable anisotropy in the spin density wave state (SDW) for both compounds, while some dissimilarities in the vicinity of the SDW transition can be attributed to the different nature of the phase change in BaFe2As2 and CaFe2As2. Temperature dependences of S and n can be described within a two-band model that contains a contribution from highly mobile, probably Dirac, electrons. The Dirac band seems to be rather isotropic, whereas most of the anisotropy in the transport phenomena could be attributed to "regular" hole-like charge carriers. We also observe that the off-diagonal element of the Peltier tensor axy is not the same for the a and b orthorhombic axes, which indicates that the widely used Mott formula is not applicable to the SDW state of iron-based superconductors.

17 pages, 7 figures

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Cited by in corpus (7)

• Thermoelectric properties of (an-)isotropic QGP in magnetic fields
• Thermoelectric anisotropy in Ba(Fe1-xCox)2As2 iron-based superconductor
• Crossover from itinerant to localized states in the thermoelectric oxide [Ca${}_2$CoO${}_3$]${}_{0.62}$[CoO${}_2$]
• Strain-derivative of thermoelectric properties: a sensitive probe for nematicity
• Multi-band effects in in-plane resistivity anisotropy of strain-detwinned disordered Ba(Fe${}_{1-x}$Ru${}_x$)${}_2$As${}_2$
• Thermoelectric signature of the nematic phase in iron-based superconductor
• Apparatus Design for Measuring of the Strain Dependence of the Seebeck Coefficient of Single Crystals