Nernst effect in single crystals of the pnictide superconductorCaFe1.92Co0.08As2and parent compound

Thermal and electrical transport in the spin density wave antiferromagnet CaFe4As3

“…Nonetheless, the magnitudes of S and ρ are comparable to those found in CaFe 2 As 2 , where ρ ≃ 0.4 mΩcm and S ≃1-2µV/K above the structure/magnetic transition temperature at 170 K. [21] This correspondence suggests that the small magnitude of S in both compounds results from a near balance of the electron and hole concentrations, and this result is confirmed for CaFe 2 As 2 in first-principle electronic structure calculations. [22] We will show below that our own electronic structure calculations, carried out using DFT, support a similar conclusion in CaFe 4 As 3 , and that this particlehole symmetry is expected in compounds with SDW transitions.…”

Nernst Effect of Iron Pnictide and Cuprate Superconductors: Signatures of Spin Density Wave and Stripe Order

“…In a pioneering study Zhu et al reported an anomalous suppression of the off-diagonal thermoelectric current in optimally doped LaFeAsO 1−x F x and suggested the presence of SDW fluctuations near the superconducting transition [19]. Matusiak et al observed a strong enhancement of the Nernst coefficient in the SDW state of the parent compounds and at low doping levels of CaFe 2−x Co x As 2 and EuFe 2−x Co x As 2 , but did not find any particular anomaly in the Nernst effect of a purely superconducting doping level that could be attributed to neither vortex flow nor to SDW fluctuations [20,21]. Kondrat et al systematically investigated the doping-evolution of the Nernst effect in LaFeAsO 1−x F x [13].…”

Suppression of backward scattering of Dirac fermions in iron pnictides Ba(Fe1−xRuxAs)Tanabe1, Huynh2, Urata3 et al. 2012Phys. Rev. B142180View full textAdd to dashboardCite

“…The absence of backward scattering holds for the geometrically identical K and K ′ points, but it is broken in the case of intervalley scattering due to the opposite chirarity [17]. In recent studies on topological insulators, a single Dirac cone emerges to create a helical spin texture at the time reversal invariant momentum In iron pnictides, almost no superconducting fluctuation has been reported in the underdoped regime of iron pnictide superconductors [18], which is in strong contrast with what has been encountered for the high temperature superconducting cuprates [19][20][21][22][23]. If the high mobility carrier could exist behind the Cooper paired electronic states, the phase coherence of Cooper pairs would be much enhanced, which can result in a robust superconducting state against thermal fluctuations.…”