Highly effective and isotropic pinning in epitaxial Fe(Se,Te) thin films grown on CaF2 substrates

Braccini, V.; Kawale, S.; Reich, Elke; Pellegrino, L.; Sala, Alberto; Putti, M.; Higashikawa, Kohei; Kiss, Takanobu; Holzäpfel, B.

doi:10.1063/1.4826677

Cited by 68 publications

(88 citation statements)

References 23 publications

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“…c-axis peak) is visible for all magnetic fields, as displayed in the inset of figure 6(c). This peak is related to correlated defects confirmed by TEM acting as effective pinning centers parallel to the c-axis [11][12][13][14].…”

Section: Resultsmentioning

confidence: 85%

“…Compared to single crystals, thin films are suitable for investigating transport properties and superconducting electronics applications thanks to their geometry. Fe(Se,Te) films have already been grown on various substrates [8][9][10][11][12][13][14], applying different lattice or thermal expansion mismatch between films and substrates. However, the role of the substrate for the superconducting properties is still not clear.…”

Section: Introductionmentioning

confidence: 99%

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Influence of substrate type on transport properties of superconducting FeSe_0.5Te_0.5thin films

Yuan¹,

Iida²,

Langer³

et al. 2015

Supercond. Sci. Technol.

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FeSe 0.5 Te 0.5 thin films were grown by pulsed laser deposition on CaF 2 , LaAlO 3 and MgO substrates and structurally and electro-magnetically characterized in order to study the influence of the substrate on their transport properties. The in-plane lattice mismatch between FeSe 0.5 Te 0.5 bulk and the substrates shows no influence on the lattice parameters of the films, whereas the type of substrates affects the crystalline quality of the films and, therefore, the superconducting properties. The film on MgO showed an extra peak in the angular dependence of critical current density J c (θ) at θ = 180° (H || c), which arises from c-axis defects as confirmed by transmission electron microscopy. In contrast, no J c (θ) peaks for H || c were observed in films on CaF 2 and LaAlO 3 . J c (θ) can be scaled successfully for both films without c-axis correlated defects by the anisotropic Ginzburg-Landau (AGL) approach with appropriate anisotropy ratio γ J . The scaling parameter γ J is decreasing with decreasing temperature, which is different from what we observed in FeSe 0.5 Te 0.5 films on Fe-buffered MgO substrates.

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Section: Resultsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Influence of substrate type on transport properties of superconducting FeSe_0.5Te_0.5thin films

Yuan¹,

Iida²,

Langer³

et al. 2015

Supercond. Sci. Technol.

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“…Further investigations on high quality Te-doped FeSe systems, possibly combining different experimental techniques, are thus mandatory. In particular, since inhomogeneities have been observed in these systems on a nanometer length scale [48,18,7], it will be important to investigate their possible effect on the optical response of a macroscopic sample portion, like that probed by an infrared beam.…”

Section: Discussionmentioning

confidence: 99%

Two-band conductivity of a FeSe$_{0.5}$Te$_{0.5}$ film by reflectance measurements in the terahertz and infrared range

Perucchi¹,

Joseph²,

Caramazza³

et al. 2014

Supercond. Sci. Technol.

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Abstract. We report an infrared spectroscopy study of a 200 nm thick FeSe 0.5 Te 0.5 film grown on LaAlO 3 with T c =13.7 K. We analyze the 20 K normal state absolute reflectance R N measured over a broad infrared range and the reflectance ratio R S /R N , R S being the superconducting state reflectance, measured at 6 K in the terahertz range down to 12 cm −1 . We show that the normal state model conductivity is given by two Drude components, one of which much broader and intense than the other. In the superconducting state, we find that a gap ∆=37±3 cm −1 opens up in the narrow Drude band only, while the broad Drude band results to be ungapped, at least in the explored spectral range. Our results show that only a two-band model can coherently describe both normal and superconducting state data. ‡ Present address: Elettra Sincrotrone Trieste,

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“…Indeed a different behavior can be observed for the same Fe(Se,Te) compound grown on different substrates 14 , by tuning the intrinsic/extrinsic pinning mechanisms. In the search for high-performance high-field superconductors, a good candidate can be the Fe(Se,Te) grown on CaF 2 substrate 15 , which shows the lowest anisotropy 16 , a very robust J c ( H ) dependence 17 , and a sufficient stability against quench under relatively high bias currents 18,19 . Additionally, in this compound the study of vortex dynamics has been recently performed at subcritical current values and in self magnetic fields 20 .…”

Section: Introductionmentioning

confidence: 99%

Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material

Grimaldi

Leo

Nigro

et al. 2018

Sci Rep

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Anisotropy effects on flux pinning and flux flow are strongly effective in cuprate as well as iron-based superconductors due to their intrinsically layered crystallographic structure. However Fe(Se,Te) thin films grown on CaF2 substrate result less anisotropic with respect to all the other iron based superconductors. We present the first study on the angular dependence of the flux flow instability, which occurs in the flux flow regime as a current driven transition to the normal state at the instability point (I*, V*) in the current-voltage characteristics. The voltage jumps are systematically investigated as a function of the temperature, the external magnetic field, and the angle between the field and the Fe(Se,Te) film. The scaling procedure based on the anisotropic Ginzburg-Landau approach is successfully applied to the observed angular dependence of the critical voltage V*. Anyway, we find out that Fe(Se,Te) represents the case study of a layered material characterized by a weak anisotropy of its static superconducting properties, but with an increased anisotropy in its vortex dynamics due to the predominant perpendicular component of the external applied magnetic field. Indeed, I* shows less sensitivity to angle variations, thus being promising for high field applications.

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Highly effective and isotropic pinning in epitaxial Fe(Se,Te) thin films grown on CaF2 substrates

Cited by 68 publications

References 23 publications

Influence of substrate type on transport properties of superconducting FeSe_0.5Te_0.5thin films

Influence of substrate type on transport properties of superconducting FeSe_0.5Te_0.5thin films

Two-band conductivity of a FeSe$_{0.5}$Te$_{0.5}$ film by reflectance measurements in the terahertz and infrared range

Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material

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Highly effective and isotropic pinning in epitaxial Fe(Se,Te) thin films grown on CaF2 substrates

Cited by 68 publications

References 23 publications

Influence of substrate type on transport properties of superconducting FeSe0.5Te0.5thin films

Influence of substrate type on transport properties of superconducting FeSe0.5Te0.5thin films

Two-band conductivity of a FeSe$_{0.5}$Te$_{0.5}$ film by reflectance measurements in the terahertz and infrared range

Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material

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Influence of substrate type on transport properties of superconducting FeSe_0.5Te_0.5thin films

Influence of substrate type on transport properties of superconducting FeSe_0.5Te_0.5thin films