Manifestations of multiple-carrier charge transport in the magnetostructurally ordered phase of BaFe2As2

Abstract

We investigated the transport properties of BaFe 2 As 2 single crystals before and after annealing with BaAs powder. The annealing remarkably improves transport properties, in particular, the magnitude of residual resistivity, which decreases by a factor of more than 10. From the resistivity measurement on detwinned crystals, we found that the anisotropy of the in-plane resistivity is remarkably diminished after annealing, indicative of dominant contributions to the charge transport from the carriers with isotropic and high mobility below magnetostructural transition temperature T s and the absence of nematic state above T s . We found that the Hall resistivity shows strong nonlinearity against magnetic field, and the magnetoresistance becomes very large at low temperatures. These results give evidence for the manifestation of multiple carriers with distinct characters in the ordered phase below T s . By analyzing the magnetic-field dependences, we found that at least three carriers equally contribute to the charge transport in the ordered phase, which is in good agreement with the results of recent quantum oscillation measurements.

Variation of transition temperatures and residual resistivity ratio in vapor-grown FeSe

“…This is reminiscent of other Fe-based compounds. For example, T s of BaFe 2 As 2 was found to increase from 136 K to 142 K on annealing 33 . Such a strong disorder dependence is consistent with an electronically-driven structural transition, often referred to as electronic nematicity in this class of materials.…”

In-plane electronic anisotropy in the antiferromagnetic orthorhombic phase of isovalent-substitutedBa(Fe1−xRux)2AsLiu1, Mikami2, Ishida3 et al. 2015Phys. Rev. BSelf Cite115240View full textAdd to dashboardCite

“…[8,12,13]. The Ru compositions of the samples were determined by energy-dispersive X-ray spectroscopy (EDXS) analysis.…”

“…The in-plane resistivity of the twinned samples was measured using a standard four-terminal method. For the measurement of inplane resistivity anisotropy, the crystals were detwinned by applying uniaxial compressive pressure and the resistivity along the a and b axes were measured using the Montgomery method as described elsewhere [12,15,16]. The measurements were performed in a Quantum Design Physical Property Measurement System (PPMS) and all the data were obtained while warming the samples.…”

“…It is interesting to study the effect of Ru substitution on the resistivity anisotropy and compare it with that of the Co-doped system. It should be noted that as-grown Ba122 crystals tend to have defects in the FeAs blocks which are most likely responsible for the observed finite resistivity anisotropy [12], confusing the study of the genuine effect of the dopants. The annealing process with BaAs powders has been demonstrated to be an effective method to reduce the crystal defects, evidenced by the remarkable reduction in the residual resistivity (RR) and an increase in the magneto-structural phase transition temperature [12,13].…”

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

“…Recently, a pronounced contribution of parabolic bands to electronic transport has been reported in Shubnikov-de Haas oscillation and Hall coefficient measurements for high quality single crystals made by annealing under BaAs [24,25]. Recent magnetoresistance measurements have reported that the Dirac cone persists in the underdoped regime of Ba(Fe 1−x Ru x As) 2 [26].…”