Critical current enhancement by Lorentz force reduction in superconductor–ferromagnet nanocomposites

Blamire, M. G.; Dinner, Rafael B.; Wimbush, Stuart C.; MacManus‐Driscoll, Judith L.

doi:10.1088/0953-2048/22/2/025017

Cited by 54 publications

(43 citation statements)

References 24 publications

(34 reference statements)

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“…8 and 10 of Ref. [17]: 10. (Color online) The size of the hysteresis in Jc (data shown as a solid line with points; red curves correspond to increasing applied field, and blue to decreasing applied field) allows comparison with the calculated predictions of several theories of magnetic pinning. The large difference between Jc on ascending and descending sweeps of the applied field expected from Lorentz force attraction (dashed curves) is not observed, nor is the substantial field shift predicted by the field compensation theory (dotted curves).…”

Section: Effect Of Magnetization On Critical Currentmentioning

confidence: 99%

Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers

Dinner

Robinson

Wimbush

et al. 2011

Supercond. Sci. Technol.

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Large area arrays of through-thickness nanoscale pores have been milled into superconducting Nb thin films via a process utilizing anodized aluminum oxide thin film templates. These pores act as artificial flux pinning centers, increasing the superconducting critical current, Jc, of the Nb films. By optimizing the process conditions including anodization time, pore size and milling time, Jc values approaching and in some cases matching the Ginzburg-Landau depairing current of 30 MA/cm 2 at 5 K have been achieved -a Jc enhancement over as-deposited films of more than 50 times. In the field dependence of Jc, a matching field corresponding to the areal pore density has also been clearly observed. The effect of back-filling the pores with magnetic material has then been investigated. While back-filling with Co has been successfully achieved, the effect of the magnetic material on Jc has been found to be largely detrimental compared to voids, although a distinct influence of the magnetic material in producing a hysteretic Jc versus applied field behavior has been observed. This behavior has been tested for compatibility with currently proposed models of magnetic pinning and found to be most closely explained by a model describing the magnetic attraction between the flux vortices and the magnetic inclusions.

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Section: Effect Of Magnetization On Critical Currentmentioning

confidence: 99%

Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers

Dinner

Robinson

Wimbush

et al. 2011

Supercond. Sci. Technol.

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“…The interaction between vortices and pinning centers has been studied extensively for decades, focused mainly on the so-called vortex core pinning (caused by the local suppression of the superconducting order parameter) [1,2]. Less explored is the interplay between vortices and magnetic media, which could offer pinning forces superior to those from core pinning [3][4][5][6]. A common difficulty of studying magnetic pinning is the inability of separating the magnetic and core contributions.…”

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confidence: 99%

Strong enhancement of the critical current at the antiferromagnetic transition in ErNi2B2C single crystals

Weigand

Civale²,

Baca³

et al. 2013

Phys. Rev. B

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We report on transport and magnetization measurements of the critical current density Jc in ErNi2B2C single crystals that show strongly enhanced vortex pinning at the Néel temperature TN and low applied fields. The height of the observed Jc peak decreases with increasing magnetic field in clear contrast with that of the peak effect found at the upper critical field. We also performed the first angular transport measurements of Jc ever conducted on this compound. They reveal the correlated nature of this pinning enhancement, which we attribute to the formation of antiphase boundaries at TN . 74.25.Sv, 74.25.Wx, 74.70.Dd Single quanta of magnetic flux enter a type II superconductor in the form of vortices when it is exposed to a magnetic field H. This is a big setback for applications, because when an electrical current J is applied, vortices move and energy is dissipated. This movement can be arrested by non-superconducting defects that pin vortices by lowering the system energy. The interaction between vortices and pinning centers has been studied extensively for decades, focused mainly on the so-called vortex core pinning (caused by the local suppression of the superconducting order parameter) [1,2]. Less explored is the interplay between vortices and magnetic media, which could offer pinning forces superior to those from core pinning [3][4][5][6]. A common difficulty of studying magnetic pinning is the inability of separating the magnetic and core contributions. It is, therefore, of great advantage to study systems where the magnetic transition takes place inside the superconducting phase, allowing one to compare the behavior with and without the magnetically ordered phase.There are a considerable number of materials in which to study the coexistence between superconductivity and ordered magnetic phases, such as the Chevrel-phases [7], CeCoIn 5 [8], and recently iron pnictides [9][10][11]. However, the rare earth-nickel-borocarbide family (RENi 2 B 2 C, where RE is a rare earth element) [12][13][14] has several advantages, namely a relatively high superconducting transition temperature T c and the tunability of the ratio between its magnetic and superconducting ordering temperatures, which can be changed by using different rare earth elements [15,16]. The readily available high-purity single crystals allow one to study the effects of magnetic pinning without any significant defect (non-magnetic) contribution [15].Among the borocarbide family the compound with RE = Er has a T c of 10.5 K and a Néel temperature T N of 6.0 K [17]. The occurrence of antiferromagnetism directly influences the superconducting properties, as seen in the upper critical field vs temperature curve, where H c2 (T ) is slightly suppressed just below T = T N for H c and has an inflection point for H ab [17]. This is a consequence of the local moments ordering in the antiferromagnetic phase, as was shown experimentally [17,18] and theoretically [19,20].In addition to the occurrence of antiferromagnetism, at T = T N a tetragonal to ortho...

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“…On the other hand, compared with core pinning by normal non-superconducting particles, the use of ferromagnetic pinning centres results in interactions between a magnetic dipole moment and flux lines, which yields a potential Upin proportional to -mb, where m is the moment of magnetic dipole and b is the field of the vortex at the distance of the dipole [34]. The deeper potential wells may reduce the Lorentz force on the vortices [35][36][37].…”

Section: Gd211 Bazro3mentioning

confidence: 99%

Improvement of Critical Current Density and Flux Trapping in Bulk High-Tc Superconductors

Izumi¹,

Noudem²

2012

Superconductors - Materials, Properties and Applications

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Critical current enhancement by Lorentz force reduction in superconductor–ferromagnet nanocomposites

Cited by 54 publications

References 24 publications

Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers

Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers

Strong enhancement of the critical current at the antiferromagnetic transition in ErNi2B2C single crystals

Improvement of Critical Current Density and Flux Trapping in Bulk High-Tc Superconductors

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