Flux motion in thin superconductors with inhomogeneous pinning

Schuster, Thomas; Kühn, H.; Brandt, Ernst Helmut; Indenbom, M. V.; Koblischka, Michael Rudolf; Kończykowski, M.

doi:10.1103/physrevb.50.16684

Cited by 90 publications

(52 citation statements)

References 64 publications

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“…In particular, they have been used to analyze magnetization curves 22,23 , magnetic relaxation data 23,24 , and ac susceptibility for various geometries 25 . Flux creep simulations have also been used to explain features of the flux penetration into thin HTSC samples in applied magnetic field 6,26 . For the first time we present here creep simulations to analyze flux dynamics in a strip with transport current and the subsequent remanent state.…”

Section: Flux Creepmentioning

confidence: 99%

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Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

et al. 1999

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Magnetic flux distribution across a high-temperature superconductor strip is measured using magneto-optical imaging at 15 K. Both the current-carrying state and the remanent state after transport current are studied up to the currents 0.97Ic where Ic is the critical current. To avoid overheating of the sample current pulses with duration 50 ms were employed. The results are compared with predictions of the Bean model for the thin strip geometry. In the current-carrying state, reasonable agreement is found. However, there is a systematic deviation -the flux penetration is deeper than theoretically predicted. A much better agreement is achieved by accounting for flux creep as shown by our computer simulations. In the remanent state, the Bean model fails to explain the experimental results. The results for the currents I ≤ 0.7Ic can be understood within the framework of our flux creep simulations. However, after the currents I > 0.7Ic the total flux trapped in a strip is substantially less than predicted by the simulations. Furthermore, it decreases with increasing current. Excessive dissipation of power in the annihilation zone formed in the remanent state is believed to be the source of this unexpected behavior.

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Section: Flux Creepmentioning

confidence: 99%

“…2-4. Most experimental studies of flux penetration, see e. g. Refs. [5][6][7][8], are focused on the behavior of samples placed in an external magnetic field, as well as on the remanent state after the field is switched-off. The results appear in a good agreement with experiment.…”

Section: Introductionmentioning

confidence: 99%

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

et al. 1999

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“…The observed flux motion in the sample is similar to that in high-Tc superconducting materials and is well agree with Bean model 6 and theoretical calculation. 7,8 However, the theoretical peaks at the edges is not clearly observed in this work since the edges of sample are not well defined and a gap exists between the indicator film and sample surface is relatively large. Figure 3 shows MO images while the sample was field cooled to 4.2 K in application of external field of 800 Oe, then the field reduced to zero.…”

Section: Experiments Detailmentioning

confidence: 69%

Magneto-optical visualization of vortices penetration into Ba(Fe1.8Co0.2)As2

Lin

Zhu

Guo

et al. 2010

Journal of Applied Physics

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Vortices penetration into oxygen-free superconducting compounds FeAs-122 system is of interest in understanding superconductivity. This work studies the vortices motion in Ba(Fe 1.8 Co 0.2 )As 2 single crystal by means of magneto-optical imaging technique in zero field cooled and field cooled conditions. The captured magneto-optical images and corresponding flux profiles show that at zero field cooled condition vortices penetrate into the crystal from the edges as external magnetic field increases. A vortices-free region is observed at the center of sample as applied field is less than full penetration field. In field cooled condition, the pinned vortices leave the sample from the edges as field decreases and polarization of the vortices at the edges are opposite as decreasing field approaches to zero. The pinning strength is decreases with increasing temperature. The observed vortex behaviour is very similar to that in high T c superconducting materials with strong pinning strength.

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“…and the thermodynamic critical field B T h , for a bias field Bx = 0.17B T h . The shown simulation is obtained without free parameters by the mesoscopic model derived from [26,27]. In the regions of reversed fields (3)-(4) a double trap is obtained, as in Fig.…”

mentioning

confidence: 99%

“…3). We simulate the magnetic history as described in the above procedure using mesoscopic models [26][27][28]. We use the simulations to find the trap distance dependence on the magnetic history.…”

mentioning

confidence: 99%

Programmable trap geometries with superconducting atom chips

et al. 2010

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We employ the hysteretic behavior of a superconducting thin film in the remanent state to generate different traps and flexible magnetic potentials for ultra-cold atoms. The trap geometry can be programmed by externally applied fields. This new approach for atom-optics is demonstrated by three different trap types realized on a single micro-structure: a Z-type trap, a double trap and a bias field free trap. Our studies show that superconductors in the remanent state provide a new versatile platform for atom-optics and applications in ultra-cold quantum gases.PACS numbers: 37.10.Gh, 03.75.Be, 74.78.NaThe use of superconductors in atom chips [1-3] is a recent development, presenting new opportunities for atom optics [4][5][6][7][8]. One demonstrated advantage of superconductors over conventional conductors is the significant reduction of near-field noise in current-carrying structures leading to low atomic heating rates and enhanced spin-flip lifetimes [9][10][11][12][13][14]. Proposals in this area advocate experimental designs for coherent coupling with atomic or molecular quantum systems that exploit the distinct properties of superconductors [15][16][17][18][19][20][21][22].In a previous paper we have demonstrated that the remanent magnetization created by vortices can be used to trap ultra cold atoms without applying a transport current [23]. Other groups have created quadrupole type traps [24] and have shown that vortices modify the trapping potential created by a transport current in a Z-type trap [25]. In this article, we show that the unique response of superconductors to applied magnetic field enables programmable magnetic trap geometries for ultra cold atoms. We demonstrate this new approach by generating three different atom trap geometries on a fixed superconducting micro-structure. We can choose the geometry by applying a suitable external magnetic field sequence. The trapping potentials are generated by spatial magnetic patterns imprinted on a thin film, using the hysteretic response of type-II superconductors.The three different geometries we realize in this article to demonstrate this new approach are shown schematically in Fig.

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Flux motion in thin superconductors with inhomogeneous pinning

Cited by 90 publications

References 64 publications

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

Magneto-optical study of magnetic-flux penetration into a current-carrying high-temperature-superconductor strip

Magneto-optical visualization of vortices penetration into Ba(Fe1.8Co0.2)As2

Programmable trap geometries with superconducting atom chips

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