Anomalous vortex dynamics in

Okuma, S.; Ichimura, Teijiro; Takeya, Hiroyuki; Hirata, Kazuto

doi:10.1016/j.physc.2009.05.212

Cited by 6 publications

(5 citation statements)

References 27 publications

(37 reference statements)

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“…Quite recently, a seemingly similar critical dynamics of vortices was reported in NbS 2 single crystals, where an unusual depinning current I h d was observed above the ordinary depinning current I d [38]. The existence of the 'second' depinning current I h d was reported earlier in the N -shaped I -V characteristics for YNi 2 B 2 C single crystals [48,49]. The authors of [38] interpreted it in terms of the jammed vortex state.…”

Section: Methodssupporting

confidence: 70%

“…They found that V (t) in response to the dc drive exhibits large-amplitude fluctuations and their lifetime diverges from both sides of I h d . The nature of jamming in vortex flow, as well as that of the second depinning current [48,49], is nontrivial and not fully clarified. In our amorphous films a sign of jamming or the second depinning current has not been found so far, implying that the vortex states studied in NbS 2 single crystals [38] are much different from ours, probably much more complicated.…”

Section: Methodsmentioning

confidence: 99%

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Critical behavior associated with transient dynamics near the depinning transition

Okuma

Motohashi

2012

New J. Phys.

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We study the general phenomenon of plastic depinning using a vortex system confined in a Corbino-disc superconductor. For an ordered initial vortex configuration, the vortices driven by a suddenly applied dc current (force) are gradually pinned to random pinning centers, indicating dynamic disordering. This is detected from the decaying of voltage V (t) (mean velocity) toward a steady-state value V ∞ . On the other hand, when the initial configuration is disordered, a gradual increase of V (t) toward V ∞ is observed, reflecting dynamic ordering. In both cases, relaxation times to reach the steady state exhibit a power-law divergence at the depinning current. Our results clearly show that the transient response depends on the initial vortex configurations: however, the transient time as well as the final mean vortex velocity only depends on the applied current, and the critical behaviors of the depinning transition are identical. To the best of our knowledge, this work is the first to demonstrate this fact predicted by numerical simulations and other more indirect experiments (e.g. Pérez Daroca et al 2011 Phys. Rev. B 84 012508).

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Section: Methodssupporting

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Critical behavior associated with transient dynamics near the depinning transition

Okuma

Motohashi

2012

New J. Phys.

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“…one can argue that the two J c values associated in the equilibrium magnetization measurements are purely due to the structural changes of the vortex lattice. Such an existence of two J c 's supports the fact that has already been reported in YNi 2 B 2 C in driven vortex systems from transport experiments [4]. The vortex lattice structure associated with the new M-H loop is more stable in structure because the forward and reverse curves of the minor hysteresis loops are merging with it.…”

Section: Resultssupporting

confidence: 87%

“…These phases and the phase boundaries are affected by the pinging strength in the crystal. Recently it was discovered that YNi 2 B 2 C have two critical depinning currents which is speculated to arise from a structural reorientation transition of the vortex lattice [1,2,4]. Ca 3 Rh 4 Sn 13 is one of the favored materials to study the characteristics of vortex matter in superconductors having a cubic crystal structure.…”

Section: Introductionmentioning

confidence: 99%

Observation of two critical current densities in a weakly pinned single crystal of Ca[sub 3]Rh[sub 4]Sn[sub 13]

Suresh¹,

Thamizhavel²,

Ramakrishnan³

et al. 2013

AIP Conference Proceedings

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“…Usually, the application of large driving current anneals a high I c state into a relatively well ordered low I c vortex state 10 . However studies in YNi 2 B 2 C crystals 17 and melt spun Fe x Ni 1−x Zr 2 samples 18 have shown that at large driving currents the driven vortex state can also enter a high I c state. A recent study 19 in a single crystal of 2H-NbS 2 shows a drive induced abrupt transformation from a moving to an immobile vortex state with a high critical current, .…”

Section: Introductionmentioning

confidence: 99%

Negative velocity fluctuations and non-equilibrium fluctuation relation for a driven high critical current vortex state

Bag

Shaw

Banerjee

et al. 2017

Sci Rep

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Under the influence of a constant drive the moving vortex state in 2H-NbS2 superconductor exhibits a negative differential resistance (NDR) transition from a steady flow to an immobile state. This state possesses a high depinning current threshold () with unconventional depinning characteristics. At currents well above , the moving vortex state exhibits a multimodal velocity distribution which is characteristic of vortex flow instabilities in the NDR regime. However at lower currents which are just above , the velocity distribution is non-Gaussian with a tail extending to significant negative velocity values. These unusual negative velocity events correspond to vortices drifting opposite to the driving force direction. We show that this distribution obeys the Gallavotti-Cohen Non-Equilibrium Fluctuation Relation (GC-NEFR). Just above , we also find a high vortex density fluctuating driven state not obeying the conventional GC-NEFR. The GC-NEFR analysis provides a measure of an effective energy scale (E eff) associated with the driven vortex state. The E eff corresponds to the average energy dissipated by the fluctuating vortex state above . We propose the high E eff value corresponds to the onset of high energy dynamic instabilities in this driven vortex state just above .

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Anomalous vortex dynamics in

Cited by 6 publications

References 27 publications

Critical behavior associated with transient dynamics near the depinning transition

Critical behavior associated with transient dynamics near the depinning transition

Observation of two critical current densities in a weakly pinned single crystal of Ca[sub 3]Rh[sub 4]Sn[sub 13]

Negative velocity fluctuations and non-equilibrium fluctuation relation for a driven high critical current vortex state

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