Kwok<i>et al</i>. reply

Kwok, W. K.; Welp, U.; Crabtree, G. W.; Vandervoort, K G; Hulscher, R.; Jz, Liu

doi:10.1103/physrevlett.64.2963

Cited by 57 publications

(88 citation statements)

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“…TPs strongly affect pinning and dynamics of vortices [23][24][25]. In particular, being plane defects they form channels of easy vortex motion along the plane of twins [24,25].…”

Section: T=t/(t C -∆T Irr ) (B)mentioning

confidence: 99%

Effect of electron irradiation on vortex dynamics inYBa2Cu3O7<

et al. 2001

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We report on drastic change of vortex dynamics with increase of quenched disorder: for rather weak disorder we found a single vortex creep regime, which we attribute to a Bragg-glass phase, while for enhanced disorder we found an increase of both the depinning current and activation energy with magnetic field, which we attribute to entangled vortex phase. We also found that introduction of additional defects always increases the depinning current, but it increases activation energy only for elastic vortex creep, while it decreases activation energy for plastic vortex creep.PACS numbers: 74.60. Jg, 74.60.Ge, 74.60.Ec, 74.72.Bk The effect of random pinning on crystalline order and on dynamics of the flux-line-lattice (FLL) was a subject of numerous experimental and theoretical investigations. . The field H on was interpreted as a phase boundary between low field ordered and high field disordered vortex phases. These experimental results are supported by theoretical studies. It was shown that in presence of rather weak disorder the FLL retains a quasilong-range order resulting in the so-called Bragg glass phase [4]. However, with the increase of random pinning or magnetic field a transition to strongly disordered entangled vortex phase (glass phase) is predicted [5,6]. A sharp increase in magnetization below the fish-tail peak position H p was observed in N d 1.85 Ce 0.15 CuO 4−d [7] and non twinned YBa 2 Cu 3 O 7−δ [8] single crystals.Magnetic measurements showed that in optimally doped YBa 2 Cu 3 O 7−δ crystals no fishtail behavior is observed both in detwinned [9] and twinned [10] samples, while decrease of the oxygen content always induced non monotonous J m (H)-curves. Two distinctive peculiarities in the magnetization curves of oxygen deficient [10] and electron irradiated [11] crystals were observed: (1) the peaks H on and H p shift toward lower magnetic fields with increasing defect concentration, and (2) in magnetic fields H < H p the current J m increases, while in magnetic fields H > H p the current J m decreases with increasing defect concentration. It is believed [12,13] that the peak H p separates elastic vortex creep in low and plastic vortex creep, mediated by motion of the FLL dislocations, in high magnetic fields. Thus the introduction of additional defects leads to an increase of vortex pinning in the region of elastic creep and such behavior is expected. On the other hand, decrease of pinning force with increasing disorder observed in the region of plastic creep is non trivial, and reasons of such behavior are not known. The aim of this paper is to show the effect of point-like defects concentration on vortex dynamics and pinning parameters in YBa 2 Cu 3 O 7−δ single crystals.The investigated sample was YBa 2 Cu 3 O 7−δ single crystal with T c ≈ 93.5 K and ∆T c < 0.5 K. Twin planes (TP's) inside the measured part of the sample were aligned in one direction. The transport current was applied along the ab-plane and at an angle α = 45 • with respect to TP's. Measurements were performed in magnet...

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“…TPs strongly affect pinning and dynamics of vortices [23][24][25]. In particular, being plane defects they form channels of easy vortex motion along the plane of twins [24,25].…”

Section: T=t/(t C -∆T Irr ) (B)mentioning

confidence: 99%

Effect of electron irradiation on vortex dynamics inYBa2Cu3O7<

et al. 2001

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“…We observe this maximum for Hу1 T. The width of this peak, ϳ5°, is in the typical range of reported trapping angles for twins. [3][4][5]9,10 On the other hand, the fact that the peak is mounted over an inclined background implies that vortices are also trapped by the tracks. Thus vortices in this angular range contain segments both in the tracks and in the twins.…”

mentioning

confidence: 99%

“…13 Many experiments have confirmed the directional pinning due to columnar defects, twins, and Cu-O planes. [1][2][3][4][5][6][7][8][9][10][11] Evidence for a locked-in phase arises from the observation of the transverse Meissner effect, 10 but a quantitative determination of L (H,T) for columnar defects had not been done until now. The introduction of columnar defects inclined with respect to the crystallographic axis has been used 1,[6][7][8]10,11 to discriminate their pinning effects from those due to twin boundaries, and from anisotropy effects.…”

mentioning

confidence: 99%

“…As threedimensional vortex configurations cannot be directly observed, our knowledge is mostly based on the analysis of the angular dependence of magnetization, susceptibility, or transport data. [1][2][3][4][5][6][7][8][9][10][11] According to theoretical models, 12,13 when the angle between the applied field H and the defects is smaller than the lock-in angle L vortices remain locked into the defects thus producing a transverse Meissner effect. For tilt angles larger than L and smaller than a trapping angle T , vortices form staircases with segments pinned into different defects and connected by unpinned or weakly pinned kinks.…”

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Evidence for vortex staircases in the whole angular range due to competing correlated pinning mechanisms

et al. 1999

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We present measurements of the angular dependence of the irreversible magnetization of YBa 2 Cu 3 O 7 single crystals with columnar defects inclined with respect to the c axis. At high fields a sharp maximum centered at the tracks direction is observed. At low fields we identify a lock-in phase characterized by an angleindependent pinning strength and observe an angular shift of the peak towards the c axis that originates in the misalignment between vortices and applied field in anisotropic materials. The interplay among columnar defects, twins, and intrinsic pinning by the ab planes generates a variety of staircase structures. We show that correlated pinning dominates for all orientations of the applied field. ͓S0163-1829͑99͒09417-5͔A difficult aspect of the study of vortex dynamics in hightemperature superconductors in the presence of correlated disorder is the determination of flux structures for applied fields tilted with respect to the pinning potential. As threedimensional vortex configurations cannot be directly observed, our knowledge is mostly based on the analysis of the angular dependence of magnetization, susceptibility, or transport data. [1][2][3][4][5][6][7][8][9][10][11] According to theoretical models, 12,13 when the angle between the applied field H and the defects is smaller than the lock-in angle L vortices remain locked into the defects thus producing a transverse Meissner effect. For tilt angles larger than L and smaller than a trapping angle T , vortices form staircases with segments pinned into different defects and connected by unpinned or weakly pinned kinks. Beyond T , vortices will be straight and take the direction of the applied field, thus being unaffected by the correlated nature of the pinning. In principle, this picture should apply with minor differences to twins, columnar defects, and intrinsic pinning. 13 Many experiments have confirmed the directional pinning due to columnar defects, twins, and Cu-O planes. 1-11 Evidence for a locked-in phase arises from the observation of the transverse Meissner effect, 10 but a quantitative determination of L (H,T) for columnar defects had not been done until now. The introduction of columnar defects inclined with respect to the crystallographic axis has been used 1,6-8,10,11 to discriminate their pinning effects from those due to twin boundaries, and from anisotropy effects. However, the vortex staircase configurations resulting from the combined effect of the various correlated structures had not yet been explored in detail.In this work we report studies of the vortex pinning in YBa 2 Cu 3 O 7 crystals with inclined columnar defects, for the whole range of field orientations. This allows us to determine the misalignment between the applied and internal fields due to anisotropy, as well as to identify the angular range of influence of each correlated pinning structure. We present the first determination of the lock-in angle of tracks using irreversible magnetization.The crystal used in this study was grown by the self-flux method, 14 and ...

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“…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]. Скорость диссипации энергии на длину вихря зависит от произведения силы Лоренца на скорость движения вихря [14,15], а посколь-ку движение вихря возникает вследствие силы Лоренца, скорость вихря пропорциональна sin θ, что приводит к выражению R ∼ sin 2 θ.…”

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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Kwoket al. reply

Cited by 57 publications

References 3 publications

Effect of electron irradiation on vortex dynamics inYBa2Cu3O7<

Effect of electron irradiation on vortex dynamics inYBa2Cu3O7<

Evidence for vortex staircases in the whole angular range due to competing correlated pinning mechanisms

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

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