Temperature and field dependence of the flux pinning mechanisms in Fe 1.06 Te 0.6 Se 0.4 single crystal

Hossaini, Sayed Jaber; Ghorbani, Shaban Reza; Arabi, Hadi; Wang, X.L.; Lin, C. T.

doi:10.1016/j.ssc.2016.07.030

Cited by 6 publications

(6 citation statements)

References 27 publications

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“…The as-grown sample only exhibits a small hysteresis loop and the magnetisation decreases rapidly with increasing field below 0.5 T and continues to drop steadily above 0.5 T. Similar to the ZFC-FC measurements presented above, we found that air annealing drastically increased the observed magnetisation for the whole measured field range and the field loop is highly symmetric for increasing and decreasing field, which suggests the presence of strong bulk pinning [34][35][36][37]. For fields B>0.5 T, the magnetisation decreases very slowly with increasing field and contrary to previous reports of compounds with slightly different selenium content [16,[38][39][40][41], no secondary peak, also known as the fishtail-effect, is observed within the measured magnetic field range. Surprisingly, prolonged annealing led to a drastic change in the symmetry of the field loop (light blue curve).…”

Section: Resultssupporting

confidence: 78%

Thermal post processing of FeSe_1−xTe _x : formation of surface iron oxides and enhancement of J _c

Uhrig

Williams

Bioletti

et al. 2019

Supercond. Sci. Technol.

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We present the results from structural analysis of single crystalline FeSe1−xTex and magnetisation measurements of as-grown FeSe0.35Te0.65 samples and after they have been annealed in air. Raman spectroscopy revealed that air annealing leads to the formation of hematite (α-Fe2O3) and magnetite (Fe3O4) on the surface of FeSe1−xTex, with the bulk beneath being free of iron oxide. Furthermore, we observe an increase in the superconducting transition temperature, Tc, from 7 to 14 K, and in the critical current density, Jc, by one order of magnitude for all applied magnetic fields. A comparison of two FeSe0.35Te0.65 samples of different thickness indicates a possible size dependence for the optimal annealing conditions. Annealing for a second time (prolonged annealing) was found to induce a surface barrier, indicated by the transition from a symmetric to a highly asymmetric magnetic hysteresis loop.

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Section: Resultssupporting

confidence: 78%

Thermal post processing of FeSe_1−xTe _x : formation of surface iron oxides and enhancement of J _c

Uhrig

Williams

Bioletti

et al. 2019

Supercond. Sci. Technol.

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“…For fields lower than 3 T, the strong pinning model starts to fail to describe satisfactorily the behavior of our data, its fits getting worse as the magnetic field decreases. It is important to underline that the morphological analysis performed on our sample (and on samples from the same batch) effectively confirms the presence of correlated disorder in terms of twin boundaries [31,32,46,81] (see figure 8), which can act as strong pinning centers at high field in particular, where the point-like defects are not effective anymore.…”

Section: Resultssupporting

confidence: 54%

“…Bonura et al [37] observe δl type single pinning crossover (low fields) to strongly interacting vortices (high fields). Other studies on FeSeTe with peak effect using Dew-Hughes analysis [39] identify the presence of normal core point pinning centers, probably related to Fe-inclusion clusters, inhomogeneous Te dopant distribution and/or planar strong pinning centers (twin boundaries) [31][32][33]38], and finally even quantum creep effects [27]. It seems that in this case the peak effect is of a field-induced type as a consequence of the active role of the twin boundaries as strong pinning centers at high magnetic fields [40].…”

Section: Introductionmentioning

confidence: 97%

“…The vortex matter in FeSeTe, and particularly the peak effect, have been investigated in detail mainly in single crystals [25][26][27][28][29][30][31][32][33][34][35][36][37]. It is important to note that the nature of the observed effects is strongly influenced by the material structure (Fe excess and Se/Te stoichiometric ratio) and sample morphology (amount and type of structural disorder), even for identically prepared crystals.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of pinning crossover and the role of twin boundaries in the peak effect in FeSeTe iron based superconductor

Galluzzi

Buchkov

Tomov

et al. 2017

Supercond. Sci. Technol.

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The correlation between the appearance of a peak effect in the critical current of a superconducting material and the presence of twin boundaries, involved in a crossover between different pinning regimes, is investigated by means of dc magnetic measurements on a FeSe0.5Te0.5 crystal. In particular, by analyzing the temperature dependence of the critical current density Jc(T) for different magnetic fields H, a crossover from a weak pinning regime to a strong pinning regime has been revealed. The analysis shows that this crossover can be ascribed to the presence of twin boundary defects inside the sample, and can be associated to the onset of the peak effect and interpreted as the start of the vortex dynamic processes responsible for the increase of Jc with the field. On the basis of the information extracted by our analysis, a plausible dynamic scenario involving the contribution of the different pinning regimes depending on the applied field has been described, and the relative H(T) vortex phase diagram has been determined. Moreover, in our description, the peak in the Jc(H) curve corresponds to the end of the processes leading to the peak effect and it is confirmed to be related to the transition from an elastic to a plastic deformation regime in the vortex lattice.

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“…which can generate the interesting second magnetization peak phenomenon. It is characterized by an anomalous increasing trend of J c with increasing magnetic fields [27][28][29][30][31][32][33] which attracts even more interest to the samples presenting this phenomenon due to their capability to sustain high currents at high magnetic fields. In this work, we present an analysis of the pinning properties of a single crystal having twin boundaries in the case of a magnetic field applied along its largest face (H||ab).…”

Section: Introductionmentioning

confidence: 99%

High Pinning Force Values of a Fe(Se, Te) Single Crystal Presenting a Second Magnetization Peak Phenomenon

et al. 2021

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The magnetization M of an Fe(Se, Te) single crystal has been measured as a function of temperature T and dc magnetic field H. The sample properties have been analyzed in the case of a magnetic field parallel to its largest face H||ab. From the M(T) measurement, the Tc of the sample and a magnetic background have been revealed. The superconducting hysteresis loops M(H) were between 2.5 K and 15 K showing a tilt due to the presence of a magnetic signal measured at T > Tc. From the M(H) curves, the critical current density Jc(H) has been extracted at different temperatures showing the presence of a second magnetization peak phenomenon. By extracting and fitting the Jc(T) curves at different fields, a pinning regime crossover has been identified and shown to be responsible for the origin of the second magnetization peak phenomenon. Then, the different kinds of pinning centers of the sample were investigated by means of Dew-Hughes analysis, showing that the pinning mechanism in the sample can be described in the framework of the collective pinning theory. Finally, the values of the pinning force density have been calculated at different temperatures and compared with the literature in order to understand if the sample is promising for high-current and high-power applications.

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Temperature and field dependence of the flux pinning mechanisms in Fe 1.06 Te 0.6 Se 0.4 single crystal

Cited by 6 publications

References 27 publications

Thermal post processing of FeSe_1−xTe _x : formation of surface iron oxides and enhancement of J _c

Thermal post processing of FeSe_1−xTe _x : formation of surface iron oxides and enhancement of J _c

Evidence of pinning crossover and the role of twin boundaries in the peak effect in FeSeTe iron based superconductor

High Pinning Force Values of a Fe(Se, Te) Single Crystal Presenting a Second Magnetization Peak Phenomenon

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Temperature and field dependence of the flux pinning mechanisms in Fe 1.06 Te 0.6 Se 0.4 single crystal

Cited by 6 publications

References 27 publications

Thermal post processing of FeSe1−x Te x : formation of surface iron oxides and enhancement of J c

Thermal post processing of FeSe1−x Te x : formation of surface iron oxides and enhancement of J c

Evidence of pinning crossover and the role of twin boundaries in the peak effect in FeSeTe iron based superconductor

High Pinning Force Values of a Fe(Se, Te) Single Crystal Presenting a Second Magnetization Peak Phenomenon

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Thermal post processing of FeSe_1−xTe _x : formation of surface iron oxides and enhancement of J _c

Thermal post processing of FeSe_1−xTe _x : formation of surface iron oxides and enhancement of J _c