Influence of an external magnetic field on the current–voltage characteristics and transport critical current density

Kiliç, A.; Kılıç, Kıvılcım; Sénoussi, S.; Demir, Kerem

doi:10.1016/s0921-4534(97)01687-0

Cited by 33 publications

(15 citation statements)

References 82 publications

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“…Here, l 0 (¼ 4p Â 10 À7 H/m) is the permeability of free space, J is the current density, and c is the geometric parameter of the sample given as c ¼ ds/2(d þ s), where s is the width and d is the thickness of the prism. [46][47][48][49][50] The slab used for the transport measurements has length l $ 5.3 mm, width s $ 1 mm, and thickness d $ 0.2 mm. Thus, the magnitude of the self-field is estimated as $0.01 mT for a transport current of 28 mA, which is about 3 orders of magnitude less than the external magnetic fields used in this study.…”

Section: Discussionmentioning

confidence: 99%

Organization of flux line system and voltage oscillations in superconducting MgB2

Kiliç

Olutaş

Kılıç

et al. 2011

Journal of Applied Physics

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The influence of bidirectional square wave (BSW) current on the evolution of the V-t curves was studied in a polycrystalline sample of MgB 2 . Regular sinusoidal-like voltage oscillations were observed at well-defined values of the amplitude (I BSW ) and period (P I ) of the BSW current, temperature, and external magnetic field. The voltage oscillations were interpreted mainly in terms of short-and long-range spatial correlations in a flux line system, relaxation effects, and the dynamic competition between pinning and depinning. The oscillating mode was also discussed in terms of sliding charge density waves associated with density fluctuations. Alternatively, the coupling between conventional thermally activated flux creep theory and annealing of the disordered states was considered as another possible mechanism in describing the voltage oscillations. Due to the complex interplay of pinning and driving forces, the oscillating mode is correlated to the drifting of flux lines, which are in motion, and it is assumed that the majority of flux lines try to traverse the sample, but do not leave it entirely. The symmetry in voltage oscillations was attributed to the equality between flux exit and entry along the sample edges. In this process, the majority of flux lines leave the sample and the direction of motion of flux lines reverses. During the oscillatory motion, we suggest that the interaction between flux lines and pinning centers may be elastic coupling in nature, because of rigidity of the flux line lattice in MgB 2 . Non-oscillatory behavior of V-t curves measured for BSW drive with low P I was attributed pre-dominantly to the effect of pinning on the distribution of the flux lines. The vortex capacitor model could be applied to explain the voltage decays in these V-t curves. However, the voltage decays associated with switching of I BSW to dc current (I dc ) were correlated to current-induced quenched disorder and to the glassy state relaxation. Further, angular dependence of voltage oscillations reveals that the anisotropic effects are nearly negligible on the evolution of V-t curves. It was shown that the voltage oscillations can be described well by an empirical expression V(t) $ sin(wt þ /), where w is the frequency and / is the phase angle. Finally, at well-defined values of I BSW and P I of BSW current, H, and T, it was argued that the MgB 2 sample behaves like a double-integrator.

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Section: Discussionmentioning

confidence: 99%

Organization of flux line system and voltage oscillations in superconducting MgB2

Kiliç

Olutaş

Kılıç

et al. 2011

Journal of Applied Physics

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“…According to the Kim model, the critical current of YBCO can be represented as the following [13]: (1) where is the self magnetic field. is the characteristic field given as , which equals 0.022 T [11], is flux quantum, is the London penetration depth, which equals 180 nm [14], and is the average radius of the grains. can be formulated with (2) where is the critical temperature of YBCO bulk.…”

Section: B Quenching Resistivity Of Ybcomentioning

confidence: 99%

“…After obtaining the magnetic potential vector distribution, we can calculate the magnetic flux density distribution with (11) where the components of the magnetic flux density are zero except the -component due to the axial symmetric characteristic.…”

Section: Thermal-electromagnetic Coupled Processmentioning

confidence: 99%

Numerical Analyses of Electrical Contact Characteristics of YBCO Bulk With Silver Deposition

Jian

Rong

et al. 2007

IEEE Trans. Appl. Supercond.

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In this paper, an axial symmetric model is constructed to investigate the electrical contact characteristics of YBCO bulk with silver deposited on the contact surface. In order to calculate the thermal-electromagnetic coupling characteristics near the contact spot, a series expression is derived to describe the quenching behavior of YBCO bulk based on the power law and Kim model and a detailed thermal-electromagnetic coupling process is presented according to the physical quenching process of YBCO bulk. During the calculation, the thermal field, the electrical field, and the self-magnetic field are coupled with each other. The calculated contact resistances are compared with the experimental ones. Agreements between them verify the effectiveness of the axial symmetric model. At last, a detailed description about the contact resistance changing from the low-impedance state to the high-impedance state is given based on the calculated field distributions. This work could be helpful to further understanding the electrical contact characteristics of YBCO bulk.

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“…Известно, что гранулярные высокотемпературные сверхпроводники (ВТСП) демонстрируют анизотропию магнитосопротивления R(H) и резистивного перехода R(T ) при различной взаимной ориентации магнитного поля H и транспортного тока j (здесь и далее вектор j соответствует макроскопическому направлению тока, протекающего через образец) [1][2][3][4][5][6][7][8][9][10][11][12][13]. С одной стороны, это неудивительно, поскольку в классическом рассмот-рении Бардина-Стефена для сверхпроводников второго рода зависящее от угла θ = ∠H, j магнитосопротивле-ние пропорционально sin 2 θ [14].…”

Section: Introductionunclassified

Анизотропия Магниторезистивных Свойств Гранулярных Высокотемпературных Сверхпроводников Как Результат Сжатия Магнитного Потока В Межгранульной Среде

Семёнов¹,

Балаев²,

Почекутов³

et al. 2017

Физика Твердого Тела

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С целью выяснения причины известной анизотропии магниторезистивных свойств гранулярных высо-котемпературных сверхпроводников (ВТСП), связанной со взаимной ориентацией магнитного поля H и транспортного тока j, исследовано поведение гистерезисных зависимостей магнитосопротивления R(H) образца ВТСП иттриевой системы при перпендикулярной (H ⊥ j) и параллельной (H j) конфигурациях. На основании концепции эффективного поля в межгранульных границах (через которые туннелируют носители сверхпроводящего тока) проведен анализ гистерезисных зависимостей R(H). Величина параметра, характе-ризующего эффективную степень сжатия магнитного потока в межгранульной среде, для перпендикулярной конфигурации оказалась примерно в 2 раза больше, чем для параллельной. Такой подход хорошо объясняет наблюдаемую многими авторами анизотропию магниторезистивных свойств гранулярных ВТСП (включая и данные по температурным зависимостям сопротивления в области резистивного перехода).Исследование выполнено при финансовой поддержке РФФИ, Правительства Красноярского края, Краевого фонда наука в рамках научного проекта № 16-48-243018.

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Influence of an external magnetic field on the current–voltage characteristics and transport critical current density

Cited by 33 publications

References 82 publications

Organization of flux line system and voltage oscillations in superconducting MgB2

Organization of flux line system and voltage oscillations in superconducting MgB2

Numerical Analyses of Electrical Contact Characteristics of YBCO Bulk With Silver Deposition

Анизотропия Магниторезистивных Свойств Гранулярных Высокотемпературных Сверхпроводников Как Результат Сжатия Магнитного Потока В Межгранульной Среде

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