Disorder-Induced Transition to Entangled Vortex Solid in Nd-Ce-Cu-O Crystal

Giller, D.; Shaulov, A.; Prozorov, Ruslan; Abulafia, Y.; Wolfus, Y.; Burlachkov, L.; Yeshurun, Y.; Zeldov, E.; Vinokur, V. M.; Peng, Jie; Greene, R. L.

doi:10.1103/physrevlett.79.2542

Cited by 151 publications

(152 citation statements)

References 25 publications

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“…1 of Ref. [123] illustrates a very successful phenomenological fit to the experimental data on the BrG-MG phase boundary in NCCO. This phase boundary was assigned to the locus of onset points of the fishtail anomaly.…”

Section: Comparison To Experimental Resultsmentioning

confidence: 99%

Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Menon

2002

Phys. Rev. B

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A general phenomenology for phase behaviour in the mixed phase of type-II superconductors with weak point pinning disorder is outlined. We propose that the "Bragg glass" phase generically transforms via two separate thermodynamic phase transitions into a disordered liquid on increasing the temperature. The first transition is into a glassy phase, topologically disordered at the largest length scales; current evidence suggests that it lacks the longranged phase correlations expected of a "vortex glass". This phase has a significant degree of short-ranged translational order, unlike the disordered liquid, but no quasi-long range order, in contrast to the Bragg glass. This glassy phase, which we call a "multi-domain glass", is confined to a narrow sliver at intermediate fields, but broadens out both for much larger and much smaller field values. The multi-domain glass may be a "hexatic glass"; alternatively, its glassy properties may originate in the replica symmetry breaking envisaged in recent theories of the structural glass transition. Estimates for translational correlation lengths in the multi-domain glass indicate that * Email:menon@imsc.ernet.in 1 they can be far larger than the interline spacing for weak disorder, suggesting a plausible mechanism by which signals of a two-step transition can be obscured. Calculations of the Bragg glass-multi-domain glass and the multidomain glass-disordered liquid phase boundaries are presented and compared to experimental data. We argue that these proposals provide a unified picture of the available experimental data on both high-T c and low-T c materials, simulations and current theoretical understanding.

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Section: Comparison To Experimental Resultsmentioning

confidence: 99%

Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Menon

2002

Phys. Rev. B

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“…As a result the magnetic curves are more regular. The overall behavior resembles the SMP observed usually in high-T c superconductors [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. For this reason we "loosely" refer to these characteristic fields as H′′ smp ′′ .…”

Section: Tmis and The "Smp" In Magnetic Measurementsmentioning

confidence: 99%

“…Recent magnetic studies in Nb films [1,2,3] reported the existence of a structure that reminisces of the second magnetization peak (SMP) which is usually observed in high-T c superconductors [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. These studies concluded that for the case of Nb films the "SMP" is probably motivated by thermomagnetic instabilities (TMIs) that occur in the low-temperature regime, far below the uppercritical field [1,2,3].…”

Section: Introductionmentioning

confidence: 99%

Relaxation measurements in the regime of the second magnetization peak in Nb films

Σταμόπουλος¹,

Niarchos²

2004

Physica C: Superconductivity

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We report on magnetic measurements as a function of field, temperature and time (relaxation) in superconducting Nb films of critical temperature Tc = 9.25 K. The magnetic measurements as a function of field exhibited a "second magnetization peak" ("SMP") which in general is accompanied by thermomagnetic instabilities (TMIs). The lines H′′ smp ′′ (T ) where the "SMP" occurs and the H fj (T ) where the first flux jump in the virgin magnetization curves is observed, end at a characteristic point (To, Ho) ≈ (7.2 K,80 Oe). Relaxation measurements showed that for T < To ≈ 7.2 K the activation energy Uo and the normalized relaxation rate S exhibit non-monotonic behavior as a function either of temperature or field. The extrema observed in Uo and S coincide with the points Hon(T ) or H′′ smp ′′ (T ) of the "SMP". In the regime T > To ≈ 7.2 K both Uo and S present a conventional monotonic behavior. These results indicate that the "SMP" behavior observed in our Nb films is promoted by the anomalous relaxation of the magnetization.

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“…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.…”

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confidence: 99%

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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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Disorder-Induced Transition to Entangled Vortex Solid in Nd-Ce-Cu-O Crystal

Cited by 151 publications

References 25 publications

Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Relaxation measurements in the regime of the second magnetization peak in Nb films

Effect of electron irradiation on vortex dynamics inYBa2Cu3O7<

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