Melting of the flux line lattice

Jackson, D.J.C.; Das, Mukunda P.

doi:10.1088/0953-2048/9/9/001

Cited by 22 publications

(16 citation statements)

References 57 publications

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“…Such drastic features are associated with a first order phase transition for the lattice vortex melting. 10,11 These results are consistent with computer simulations in the three-dimensional ͑3D͒ XY model [12][13][14][15][16] and others. 17 The first-order-like transition seems to remain even in the presence of some ͑simulated through the XY exchange integral͒ static disorder 14͑b͒ but not in the presence of point defects ͑introduced by irradiation͒.…”

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confidence: 90%

Comment on “Observation of vortex-lattice melting inYBa2Cu3O7<

et al. 1999

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The findings of Ghamlouch et al. ͓Phys. Rev. B 54, 9070 ͑1996͔͒ on the jump in the thermoelectric power of high-T c superconductors below the critical temperature in the presence of large magnetic fields are discussed. The complicated interplay between the vortex lattice thermodynamic transitions and the transport property percolation transitions raises questions on their similarities, differences, and relationships with respect to the ͑B,T͒ phase diagram features and the classical Kosterlitz-Thouless transition. A few comments pertain to the experimental details and others on the relevant role of thermomagnetic transport properties.

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confidence: 90%

Comment on “Observation of vortex-lattice melting inYBa2Cu3O7<

et al. 1999

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“…In general, the Jc(H) curves have a field decrease that prevents determining the irreversibility field Hirr (evaluated as Jc ≈ 100 A/cm 2 ) even for the highest temperature shown in Figure 3 (11 K) and at 9 T. In order to deeply study the Jc(H) anomalous behavior reported in Figure 3, the Jc curves as a function of temperature Jc(T) at different fields were extracted from the Jc(H). In particular, by fitting the Jc(T) behavior with several pinning models reported in the literature [51][52][53][54][55][56][57], it is possible to determine the pinning regime acting in the sample. Among the pinning models, the three equations that best fit our experimental data across the field range are the following ones: In order to deeply study the J c (H) anomalous behavior reported in Figure 3, the J c curves as a function of temperature J c (T) at different fields were extracted from the J c (H).…”

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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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“…Similar dependencies have been introduced to account for the existence of the "giant flux creep" [60][61] , taking the pinning potential as U p = H c 2 (t) * (a 0 2 ξ), where a 0 2 = φ 0 B is the area of a unit cell of the flux lines lattice 59) . The macroscopic force F p results also in this case from a direct summation procedure of elementary pinning forces, f p =U p /λ, where λ is the London penetration depth.…”

Section: -The Non-linear Diffusion Equationmentioning

confidence: 99%

Nonuniversal temperature dependencies of the low-frequency ac magnetic susceptibility in high-Tcsuperconductors

et al. 1999

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The complex ac magnetic susceptibilities (χ n = χ' n + iχ n ") of high T c superconductors in absence of dc fields have been studied by numerically solving the non-linear diffusion equation for the magnetic flux, where the diffusivity is determined by the resistivity. In our approach the parallel resistor model between the creep and flux flow resistivities is used, so that the crossover between different flux dynamic processes (thermally activated flux flow, flux creep, flux flow) can naturally arise. For this reason we remark that, as the frequency increases, the presence of a different non linearity in different regions of the I-V characteristic determines nonuniversal temperature dependencies of the χ n , i.e. the χ n are found to be not universal functions of a frequency and temperature dependent single parameter. Moreover, the actual frequency dependent behavior is also shown to be strictly related to the particular pinning model chosen for the simulations. Indeed, for large values of the reduced pinning potential (U/KT≥220) and for increasing frequency, a transition has been observed between dynamic regimes dominated by creep and flux flow processes. On the other hand, for smaller reduced pinning potentials, a transition from the thermally activated flux flow (Taff) to the flow regime occurs. In qualitative agreement with available experimental data but in contrast with previously used simpler models, the amplitude of the peak of the imaginary part of the first harmonic is shown to be frequency dependent. Moreover the frequency dependence of its peak temperature shows large discrepancies with approximated analytical predictions. Finally, the shape of the temperature dependencies of the higher harmonics are found to be strongly affected by the frequency.

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Melting of the flux line lattice

Cited by 22 publications

References 57 publications

Comment on “Observation of vortex-lattice melting inYBa2Cu3O7<

Comment on “Observation of vortex-lattice melting inYBa2Cu3O7<

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

Nonuniversal temperature dependencies of the low-frequency ac magnetic susceptibility in high-Tcsuperconductors

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