Thermally activated flux flow in superconducting epitaxial FeSe0.6Te0.4 thin film

Ahmad, Dawood[Ahmad; Choi, Woojae; Seo, Y. I.; Seo, Se Hun[Seo; Lee, Sanghan; Kwon, Y. S.

doi:10.1016/j.rinp.2016.11.054

Cited by 27 publications

(22 citation statements)

References 31 publications

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“…The values of anisotropies H /H ⊥ are γ = 2.55 for R = 0.1R n , which corresponds primarily to the low-T c phase, and γ = 1.59 for R = 0.9R n , which corresponds primarily to the high-T c phase. Those values are consistent with previous studies on FeSe 0.6 Te 0.4 epitaxial thin films with a higher T c [41]. Figure 4(e) shows temperature dependencies of R( ) at 10 T. Here again we see the qualitative modification of R( ) curves with increasing temperature.…”

Section: A 2d Behavior In Ba 1−x Na X Fe 2 As 2 Crystalssupporting

confidence: 91%

Unusual two-dimensional behavior of iron-based superconductors with low anisotropy

et al. 2017

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We study angular-dependent magnetoresistance in iron-based superconductors Ba 1−x Na x Fe 2 As 2 and FeTe 1−x Se x . Both superconductors have relatively small anisotropies γ ∼ 2 and exhibit a three-dimensional (3D) behavior at low temperatures. However, we observe that they start to exhibit a profound two-dimensional behavior at elevated temperatures and in applied magnetic field parallel to the surface. We conclude that the unexpected two-dimensional (2D) behavior of the studied low-anisotropic superconductors is not related to layeredness of the materials, but is caused by appearance of surface superconductivity when magnetic field exceeds the upper critical field H c2 (T ) for destruction of bulk superconductivity. We argue that the corresponding 3D-2D bulk-to-surface dimensional transition can be used for accurate determination of the upper critical field.

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Section: A 2d Behavior In Ba 1−x Na X Fe 2 As 2 Crystalssupporting

confidence: 91%

Unusual two-dimensional behavior of iron-based superconductors with low anisotropy

et al. 2017

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“…Therefore, the broadening observed in magnetic fields is definitely due to the thermally activated depinning of the vortex in the vortex liquid phase. The vortex liquid state is divided into the pinned vortex liquid state and the unpinned vortex liquid state 22,23 . To distinguish between the two states, we differentiated each electrical resistivity by temperature, ρ T T d ( )/d , and plotted it as a function of temperature in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In all three samples, the data at each magnetic field shows a peak at T k (B), and the peak shifts towards lower temperatures as the magnetic field increases. The temperature range above T k (B) is due to the unpinned vortex liquid phase and the temperature area below T k (B) is due to the pinned vortex phase 22,23 . Thus the irreversibility field, H irr (T), at each temperature can be determined from T k (B) and is plotted in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This result helps to understand the vortex movement more accurately. Actually, in order to consider the temperature dependence of the prefactor ρU T 2 / c , the introduction of the nonlinear relationship of U T H ( , ) vs. T has been performed in many cuprates and iron-based superconductors 23,29,30,32 . Using the nonlinear relationship are derived.…”

Section: Resultsmentioning

confidence: 99%

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Effect of the proton irradiation on the thermally activated flux flow in superconducting SmBCO coated conductors

Choi

Ahmad

Seo

et al. 2020

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We investigate changes in the vortex pinning mechanism caused by proton irradiation through the measurement of the in-plane electrical resistivity for H//c in a pristine and two proton-irradiated (total doses of 1 × 1015 and 1 × 1016 cm−2) SmBa2Cu3O7-δ (SmBCO) superconducting tapes. Even though proton irradiation has no effect on the critical temperature (Tc), the resulting artificial point defect causes an increase in normal state electrical resistivity. The electrical resistivity data around Tc shows no evidence of a phase transition to the vortex glass state but only broadens with increasing magnetic field due to the vortex depinning in the vortex liquid state. The vortex depinning is well interpreted by a thermally activated flux flow model in which the activation energy shows a nonlinear temperature change $${\boldsymbol{U}}{\boldsymbol{(}}{\boldsymbol{T}},{\boldsymbol{H}}{\boldsymbol{)}}{\boldsymbol{=}}{{\boldsymbol{U}}}_{{\boldsymbol{0}}}{\boldsymbol{(}}{\boldsymbol{H}}{\boldsymbol{)}}{{\boldsymbol{(}}{\bf{1}}-{\boldsymbol{T}}{\boldsymbol{/}}{{\boldsymbol{T}}}_{{\boldsymbol{c}}}{\boldsymbol{)}}}^{{\boldsymbol{q}}}$$U(T,H)=U0(H)(1−T/Tc)q (q = 2). The field dependence of activation energy shows a $${{\boldsymbol{U}}}_{{\bf{0}}}{\boldsymbol{ \sim }}{{\boldsymbol{H}}}^{-{\boldsymbol{\alpha }}}$$U0~H−α with larger exponents above 4 T. This field dependence is mainly due to correlated disorders in pristine sample and artificially created point defects in irradiated samples. Compared with the vortex pinning due to correlated disorders, the vortex pinning due to the appropriate amount of point defects reduces the magnitude of Uo(H) in the low magnetic field region and slowly reduces Uo(H) in high magnetic fields.

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“…From the GL theory, the H C2 (0) values have been estimated by using the equation 1. 16 H C2 (T) = H C2 (0)(…”

Section: Resultsmentioning

confidence: 99%

Vortex state study of superconducting Fe(Te, Se) thin films deposited on SrTiO3 substrate by pulsed laser deposition technique

2019

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Superconducting thin films of two thicknesses have been fabricated on (100) oriented SrTiO 3 (STO) substrates using the target of composition Fe 1.05 Te 0.50 Se 0.50 by pulsed laser deposition technique. The structural and transport properties of the fabricated thin films have been investigated and the results indicate the enhancement in the superconducting properties with increasing thickness of the thin films. The onset of the superconducting transition temperature of the grown thin films of thicknesses ∼78 nm and ∼177 nm are ∼12.10 and 12.62 K at 0 T magnetic field, respectively. To estimate the upper critical fields H C2 (0), thermally activated energy (TAE) and vortex phase diagram, the magnetoresistance measurements have been performed in the magnetic field range of 0-8 T. H C2 (0) have been calculated by Ginzburg Landau (GL) theory and Werthamer-Helfand-Hohenberg model by taking the criterion of 90%, 50% and 10% of normal state resistivity and the corresponding GL coherence lengths have also been calculated. In the present work, the TAE has been estimated by conventional Arrhenius relation and modified thermally activated flux flow (TAFF) theory. The power law dependence of TAE, shows prominently the possible planer defects in the system. From the modified TAFF model, the values of fitting parameter 'q' suggests the 3 dimensional behaviour of the vortices for both the grown thin films. The vortex phase diagram study reveals the transition from the vortex liquid to vortex glass state.

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Thermally activated flux flow in superconducting epitaxial FeSe0.6Te0.4 thin film

Cited by 27 publications

References 31 publications

Unusual two-dimensional behavior of iron-based superconductors with low anisotropy

Unusual two-dimensional behavior of iron-based superconductors with low anisotropy

Effect of the proton irradiation on the thermally activated flux flow in superconducting SmBCO coated conductors

Vortex state study of superconducting Fe(Te, Se) thin films deposited on SrTiO3 substrate by pulsed laser deposition technique

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