Critical current density of ceramic high-temperature superconductors in a low magnetic field

Müller, K.‐H.; Matthews, David; Driver, R.

doi:10.1016/0921-4534(92)90928-6

Cited by 50 publications

(18 citation statements)

References 20 publications

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“…While most experimental studies of the field dependence of the critical current I c are being interpreted solely on the basis of bulk-pinning theory (see for example [10][11][12][13][14] ), a number of works 6,8,15,16 have shown that a geometrical edge barrier (or surface barrier) may strongly affect I c . In this paper we study the combined effect of a geometrical edge barrier and bulk pinning upon the magnetic field dependence of I c for type-II superconducting strips.…”

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confidence: 99%

Field-dependent critical current in type-II superconducting strips: Combined effect of bulk pinning and geometrical edge barrier

Elistratov¹,

Vodolazov²,

Maksimov³

et al. 2002

Phys. Rev. B

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Recent theoretical and experimental research on low-bulk-pinning superconducting strips has revealed striking dome-like magnetic-field distributions due to geometrical edge barriers. The observed magnetic-flux profiles differ strongly from those in strips in which bulk pinning is dominant. In this paper we theoretically describe the current and field distributions of a superconducting strip under the combined influence of both a geometrical edge barrier and bulk pinning at the strip's critical current Ic, where a longitudinal voltage first appears. We calculate Ic and find its dependence upon a perpendicular applied magnetic field Ha. The behavior is governed by a parameter p, defined as the ratio of the bulk-pinning critical current Ip to the geometrical-barrier critical current Is0. We find that when p > 2/π and Ip is field-independent, Ic vs Ha exhibits a plateau for small Ha, followed by the dependence Ic − Ip ∝ H −1 a in higher magnetic fields.The combination of a geometrical edge barrier and bulk pinning recently has been shown to strongly affect the properties of low-dimensional superconductors (thin films, single crystals, and tapes with high demagnetizing factors) placed in either a perpendicular magnetic field 1-5 or a transport-current-carrying state 6-9 . While most experimental studies of the field dependence of the critical current I c are being interpreted solely on the basis of bulk-pinning theory (see for example 10-14 ), a number of works 6,8,15,16 have shown that a geometrical edge barrier (or surface barrier) may strongly affect I c . In this paper we study the combined effect of a geometrical edge barrier and bulk pinning upon the magnetic field dependence of I c for type-II superconducting strips. We shall show how the dependence of I c upon H a is controlled by the parameter p = I p /I s0 , where I p is the bulk-pinning critical current in the absence of a geometrical edge barrier, and I s0 is the geometrical-barrier critical current in the absence of bulk pinning.We consider a superconducting strip of thickness d (|y| < d/2) and width 2W (|x| < W ) centered on the z axis. We assume that d is less than the London penetration depth λ and that W is much larger than the two-dimensional screening length Λ = 2λ 2 /d. The strip is subjected to a perpendicular applied magnetic field H a = (0, H a , 0), and it carries a total current I in the z direction described by a spatially dependent sheet current density K(x) = Jd = [0, 0, K z (x)]. We wish to determine the current-density and magnetic-field distributions at the critical current at which a steady-state flux-flow voltage appears along the length of the strip. For a strip containing no magnetic flux, K z (x) is the sum of two contributions,

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confidence: 99%

Field-dependent critical current in type-II superconducting strips: Combined effect of bulk pinning and geometrical edge barrier

Elistratov¹,

Vodolazov²,

Maksimov³

et al. 2002

Phys. Rev. B

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“…Þ À1 with B ? being a characteristic field of the weak links [24]. In addition, a linear relation between voltage and current has been observed at increased magnetic fields and temperatures, which indicates a dominant reversible regime in the magnetic phase diagram.…”

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confidence: 96%

High Upper Critical Fields and Evidence of Weak-Link Behavior in SuperconductingLaFeAsO1−xFxThin Films

et al. 2010

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Superconducting LaFeAsO1-xFx thin films were grown on single crystalline LaAlO3 substrates with critical temperatures (onset) up to 28 K. Resistive measurements in high magnetic fields up to 40 T reveal a paramagnetically limited upper critical field mu{0}H{c2}(0) around 77 T and a remarkable steep slope of -6.2 T K-1 near T{c}. From transport measurements we observed weak-link behavior in low magnetic fields and evidence for a broad reversible regime.

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“…[15][16][17] According to Ginzburg et al, 18 the appropriate field dependence of the critical current density for ceramic YBa 2 Ca 3 O 7Ϫx ͑YBCO͒ may be of the following form:…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the low-field magnetization of granular superconductors

Ambrico

Luca²,

Pace³

et al. 1996

Phys. Rev. B

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Calculations of low-field magnetization curves of superconducting granular systems are carried out by means of a critical-state model that follows from the Josephson-junction network description of this class of superconductors. An approximate analytical expression of the temperature-dependent effective critical current density Jc is derived. General critical-state calculations which explicitly take account of temperature effects are thus specified to the case of a cylindrically symmetric polycrystalline superconducting sample. The calculated low-field magnetic properties are seen to be in good agreement with experimental result

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Critical current density of ceramic high-temperature superconductors in a low magnetic field

Cited by 50 publications

References 20 publications

Field-dependent critical current in type-II superconducting strips: Combined effect of bulk pinning and geometrical edge barrier

Field-dependent critical current in type-II superconducting strips: Combined effect of bulk pinning and geometrical edge barrier

High Upper Critical Fields and Evidence of Weak-Link Behavior in SuperconductingLaFeAsO1−xFxThin Films

Temperature dependence of the low-field magnetization of granular superconductors

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