Multiband character ofβ-FeSe: Angular dependence of the magnetoresistance and upper critical field

Abstract

We studied ab-plane transport properties in single crystals of the superconductor β-FeSe up to 16 T. In the normal state, below 90 K, the crystals present a strongly anisotropic positive magnetoresistance that becomes negligible above that temperature. In the superconducting state (Tc=8.87(5) K) the upper critical field anisotropy Hc2 ab/ Hc2 c changes with temperature and the angular dependence of the dissipation for fixed temperatures and fields reflects a strongly anisotropic behavior. Our results make evident that multiband effects are needed to describe the measured transport properties. We model the magnetoresistance and upper critical field behavior with a two-band model showing that the diffusivities ratio parameter remains unchanged going from the normal to the superconducting state.

Microstructural control of the transport properties of β-FeSe films grown by sputtering

“…Figure 4 (b) shows the temperature dependence of the transversal magnetoresistance, ∆ρ ρ 0 = (ρ(H) − ρ 0 ) /ρ 0 , with µ 0 H = 8 and 16 T. A positive magnetoresistance is observed below the structural transition, which increases as the temperature decreases. We emphasize that this was mainly reported for bulk high-quality single crystals 31,32 , although it has also been reported for 160 nm thick PLD grown films 33 .…”

Vortex dynamics inβ-FeSe single crystals: effects of proton irradiation and small inhomogeneous stress

“…• C for 45 days [5]. The phase purity of each crystal was verified by X-ray diffraction (XRD) using a PANalytical Empyrean equipment with Ni filtered Cu K α radiation.…”

“…The electronic properties display signatures of multiband effects [4,5]. The superconducting properties are affected by chemical doping [6] and mechanical pressure [7,8].…”

Robustness of superconductivity to structural disorder inSr0.3(NH2)y(NH3)1Foronda1, Ghannadzadeh2, Sedlmaier3 et al. 2015Phys. Rev. B9040View full textAdd to dashboardCite

“…8), which may be indicative of a multiband nature. This type of behavior has been observed in other layered two-band superconductors such as the FeAsbased systems [25,26] and the parent compound FeSe using resistivity measurements [27]. Fits of the Werthamer-HelfandHohenberg (WHH) model [28] for a one-band superconductor in the dirty limit did not converge.…”