Nonequilibrium depinning transition of ac driven vortices with random pinning

Kawamura, Yasuki; Moriya, S; Ienaga, Koichiro; Kaneko, Shigeo; Okuma, S.

doi:10.1088/1367-2630/aa819d

Cited by 12 publications

(9 citation statements)

References 48 publications

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“…Relaxation times required for the system to settle into the steady state exhibit a power-law divergence at the depinning current with critical exponents 18–20 . More recently, using ac drive 21 , we have also observed the critical behavior of the depinning transition with the critical exponent close to that for the dc drive, which is the further demonstration of the universality of the nonequilibrium depinning transition 5 . In these experiments, however, the critical behavior has been observed only on the moving (fluctuating diffusing [active]) side of the transition.…”

Section: Introductionsupporting

confidence: 66%

Critical behavior near the reversible-irreversible transition in periodically driven vortices under random local shear

Maegochi

Ienaga

Kaneko

et al. 2019

Sci Rep

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When many-particle (vortex) assemblies with disordered distribution are subjected to a periodic shear with a small amplitude , the particles gradually self-organize to avoid next collisions and transform into an organized configuration. We can detect it from the time-dependent voltage (average velocity) that increases towards a steady-state value. For small , the particles settle into a reversible state where all the particles return to their initial position after each shear cycle, while they reach an irreversible state for above a threshold . Here, we investigate the general phenomenon of a reversible-irreversible transition (RIT) using periodically driven vortices in a strip-shaped amorphous film with random pinning that causes local shear, as a function of . By measuring , we observe a critical behavior of RIT, not only on the irreversible side, but also on the reversible side of the transition, which is the first under random local shear. The relaxation time to reach either the reversible or irreversible state shows a power-law divergence at . The critical exponent is determined with higher accuracy and is, within errors, in agreement with the value expected for an absorbing phase transition in the two-dimensional directed-percolation universality class. As is decreased down to the intervortex spacing in the reversible regime, deviates downward from the power-law relation, reflecting the suppression of intervortex collisions. We also suggest the possibility of a narrow smectic-flow regime, which is predicted to intervene between fully reversible and irreversible flow.

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Section: Introductionsupporting

confidence: 66%

Critical behavior near the reversible-irreversible transition in periodically driven vortices under random local shear

Maegochi

Ienaga

Kaneko

et al. 2019

Sci Rep

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“…The relaxation time for the system to settle into the moving steady state ( ) exhibits a power-law divergence at the depinning current with critical exponents = 1.4 ± 0.4 9 , 12 , 20 , within error bars, in agreement with the value expected for an absorbing phase transition in the two-dimensional (2D) directed-percolation (DP) universality class 36 – 38 . Using ac drive 39 , we have also observed the critical behavior of the depinning transition with the critical exponent close to that for the dc drive, further demonstrating the universality of the nonequilibrium depinning transition 5 .…”

Section: Introductionsupporting

confidence: 54%

“…In these experiments, however, the critical behavior of the depinning transition has been observed only on the moving (fluctuating diffusing [active]) side of the transition 9 , 12 , 20 , 39 , although that of RIT has been reported on both sides of the transition 20 , 24 , 26 . This is because it is difficult to obtain a reliable data of V ( t ) in the pinned (non-fluctuating quiescent [absorbing]) phase, where V ( t ) relaxes to = 0.…”

Section: Introductionmentioning

confidence: 99%

Critical behavior of nonequilibrium depinning transitions for vortices driven by current and vortex density

Kaji

Maegochi

Ienaga

et al. 2022

Sci Rep

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We study the critical dynamics of vortices associated with dynamic disordering near the depinning transitions driven by dc force (dc current I) and vortex density (magnetic field B). Independent of the driving parameters, I and B, we observe the critical behavior of the depinning transitions, not only on the moving side, but also on the pinned side of the transition, which is the first convincing verification of the theoretical prediction. Relaxation times, $$\tau (I)$$ τ ( I ) and $$\tau (B)$$ τ ( B ) , to reach either the moving or pinned state, plotted against I and B, respectively, exhibit a power-law divergence at the depinning thresholds. The critical exponents of both transitions are, within errors, identical to each other, which are in agreement with the values expected for an absorbing phase transition in the two-dimensional directed-percolation universality class. With an increase in B under constant I, the depinning transition at low B is replaced by the repinning transition at high B in the peak-effect regime. We find a trend that the critical exponents in the peak-effect regime are slightly smaller than those in the low-B regime and the theoretical one, which is attributed to the slight difference in the depinning mechanism in the peak-effect regime.

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“…Driven 2D VLs can be used as simple models for a small portion of the 3D vortex systems studied experimentally, for which history effects in the response have been often observed [20] and signatures of criticality at the depinning transition were reported [3,23]. A prototype of such systems is the vortex matter in clean NbSe 2 single crystals in which the stable vortex phase at low temperatures and weak magnetic fields is an ordered Bragg glass (BG) without VL dislocations [24].…”

mentioning

confidence: 99%

Alternate-current dynamic reorganization and nonequilibrium phase transition in driven vortex matter

2020

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Externally driven glassy systems may undergo nonequilibrium phase transitions (NEPTs). In particular, acdriven systems display special features, such as those observed in the vortex matter of NbSe 2 , where oscillatory drives reorganize the system into partially ordered vortex lattices. We provide experimental evidence for this dynamic reorganization and we show an unambiguous signature of its connection with an NEPT driven by ac forces. We perform a scaling analysis and we estimate critical exponents for this transition. Our results share similarities with some glass-to-viscous-liquid NEPTs and invite a search for similar physics in other elastic disordered media.

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Nonequilibrium depinning transition of ac driven vortices with random pinning

Cited by 12 publications

References 48 publications

Critical behavior near the reversible-irreversible transition in periodically driven vortices under random local shear

Critical behavior near the reversible-irreversible transition in periodically driven vortices under random local shear

Critical behavior of nonequilibrium depinning transitions for vortices driven by current and vortex density

Alternate-current dynamic reorganization and nonequilibrium phase transition in driven vortex matter

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