Magnetic flux instabilities in superconducting niobium rings: Tuning the avalanche behavior

Nowak, E. R.; Taylor, O.; Liu, Li; Jaeger, H. M.; Selinder, T. I.

doi:10.1103/physrevb.55.11702

Cited by 61 publications

(62 citation statements)

References 23 publications

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“…In addition, recent magnetic studies in Nb films [14,15] reported the existence of a structure that reminisces of the second magnetization peak (SMP) which is usually observed in high-T c superconductors [16,17,18,19,20]. These studies concluded that for the case of Nb films the "second magnetization peak" ("SMP") is motivated by thermomagnetic insta- ‡ Corresponding author (densta@ims.demokritos.gr) bilities (TMI) that occur in the low-temperature regime, far below the upper-critical field [14,15,21]. Despite the need for the complete theoretical understanding of the underlying mechanism that motivates the "SMP", the existence of the accompanying TMI should be studied experimentally in more detail, because the undesirable flux jumps constitute a serious limitation for practical applications.…”

Section: Introductionmentioning

confidence: 99%

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB₂bulk samples

Σταμόπουλος¹,

Speliotis²,

Niarchos³

2004

Supercond. Sci. Technol.

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We report on magnetic and magnetoresistance measurements in two categories of superconducting Nb films grown via magnetron sputtering and MgB−2 bulk samples. In the first category, films of Tc = 9.25 K were produced by annealing during deposition. In these films, the magnetic measurements exhibited the so-called "second magnetization peak" ("SMP"), which is accompanied by thermomagnetic instabilities (TMI). The characteristic field H fj , where the first flux jump occurs, has been studied as a function of the sweep rate of the magnetic field. Interestingly, in the regime T < 6.4 K, the respective line H fj (T ) is constant, H fj (T< 6.4 K)= 40 Oe. A comparison to TMI observed in MgB2 bulk samples is also performed. Our experimental findings can't be described accurately by current theories on TMI. In the second category, films of Tc = 8.3 K were produced without annealing during deposition. In such films, we observed a peak effect (PE). In high magnetic fields the PE is accompanied by a sharp drop and a narrow hysteretic behavior (∆T < 20 mK) in the measured magnetoresistance. In contrast to experimental works presented in the past, the comparison of our magnetic measurements with the magnetoresistance data suggests that rather the appearance of surface superconductivity than the melting transition of vortex matter, is the cause of the observed behavior.

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Section: Introductionmentioning

confidence: 99%

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB₂bulk samples

Σταμόπουλος¹,

Speliotis²,

Niarchos³

2004

Supercond. Sci. Technol.

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“…Different scenarios are considered resulting in a variety of flux patterns, e.g., magnetic turbulence [8,9], kinetic flux front roughening [10], magnetic micro avalanches [11,12], flux dendrites [13,14,15,16,17], thermomagnetic fingering [18], bending of flux-antiflux interface [19,20], and flux front corrugation [21].…”

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confidence: 99%

Ultrafast magnetic flux dendrite propagation into thin superconducting films

et al. 2005

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We suggest a new theoretical approach describing the velocity of magnetic flux dendrite penetration into thin superconducting films. The key assumptions for this approach are based upon experimental observations. We treat a dendrite tip motion as a propagating flux jump instability. Two different regimes of dendrite propagation are found: A fast initial stage is followed by a slow stage, which sets in as soon as a dendrite enters into the vortex-free region. We find that the dendrite velocity is inversely proportional to the sample thickness. The theoretical results and experimental data obtained by a magneto-optic pump-probe technique are compared and excellent agreement between the calculations and measurements is found.

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“…For a magnetic field oriented perpendicular to the Nb film surface such vortex motion leads to flux jumps [8,9]. These flux jumps were interpreted as a thermomagnetic instability of the critical state.…”

Section: Introductionmentioning

confidence: 99%

dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots

Tsindlekht¹,

Genkin²,

Felner³

et al. 2016

J. Phys.: Condens. Matter

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dc and ac magnetic properties of two thin-walled superconducting Nb cylinders with a rectangular cross-section are reported. Magnetization curves and the ac response were studied on as-prepared and patterned samples in magnetic fields parallel to the cylinder axis. A row of micron-sized antidots (holes) was made in the film along the cylinder axis. Avalanche-like jumps of the magnetization are observed for both samples at low temperatures for magnetic fields not only above Hc1, but in fields lower than Hc1 in the vortex-free region. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than Hc1. At temperatures above 0.66Tc and 0.78Tc the magnetization curves become smooth for the patterned and the as-prepared samples, respectively. The magnetization curve of a reference planar Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures. The ac response was measured in constant and swept dc magnetic field modes. Experiment shows that ac losses at low magnetic fields in a swept field mode are smaller for the patterned sample. For both samples the shapes of the field dependences of losses and the amplitude of the third harmonic are the same in constant and swept field near Hc3. This similarity does not exist at low fields in a swept mode.

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Magnetic flux instabilities in superconducting niobium rings: Tuning the avalanche behavior

Cited by 61 publications

References 23 publications

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB₂bulk samples

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB₂bulk samples

Ultrafast magnetic flux dendrite propagation into thin superconducting films

dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots

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Magnetic flux instabilities in superconducting niobium rings: Tuning the avalanche behavior

Cited by 61 publications

References 23 publications

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB2bulk samples

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB2bulk samples

Ultrafast magnetic flux dendrite propagation into thin superconducting films

dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots

Contact Info

Product

Resources

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From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB₂bulk samples

From the second magnetization peak to peak effect. A study of superconducting properties in Nb films and MgB₂bulk samples