Rotational magnetic measurements of vortex pinning in polycrystalline type-II superconductors

Hasan, M.K.; Park, S.J.; Kouvel, J. S.

doi:10.1016/0921-4534(95)00583-8

Cited by 16 publications

(7 citation statements)

References 17 publications

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“…The anisotropic properties of high-temperature superconductors have motivated measurements of their magnetization M as a function of the angle θ between the external DC magnetic field H and one of the principal axis of the superconductor. Such experiments may supply ample information regarding the superconducting properties and they were used for studies of the 3D anisotropic Ginzburg-Landau theory in single Y Ba 2 Cu 3 O 7−δ crystal [1], pinning strength distribution in polycrystalline materials [2][3][4][5][6], intrinsic anisotropy [7,8] and interaction of vortices with pinning sites and external magnetic fields [3,6,9]. The conclusions in these works were drawn from the peculiarities observed in rotation curves at different ambient conditions.…”

Section: Introductionmentioning

confidence: 99%

Irreversible magnetization in thin YBCO films rotated in external magnetic field

Prozorov

Poddar

Sheriff

et al. 1996

Physica C: Superconductivity

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The magnetization M of a thin Y Ba 2 Cu 3 O 7−δ film is measured as a function of the angle θ between the applied field H and the c− axis. For fields above the first critical field, but below the Bean's field for first penetration H * , M (θ)is symmetric with respect to θ = π and the magnetization curves for forward and backward rotation coincide. For H > H * the curves are asymmetric and they do not coincide. These phenomena have a simple explanation in the framework of the Bean critical state model.

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Section: Introductionmentioning

confidence: 99%

Irreversible magnetization in thin YBCO films rotated in external magnetic field

Prozorov

Poddar

Sheriff

et al. 1996

Physica C: Superconductivity

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“…Another confirmation of this work can be made using the rotational magnetization measurements. This allows us to find the effective pinning torque per vortex [12]. In fact, our rotational measurements on the same samples showed a seven-fold enhancement in the pinning forces at temperatures below 25 K [8].…”

Section: Resultsmentioning

confidence: 63%

Temperature dependence of vortex flux pinning with γ-irradiation in polycrystalline Tl-2223

Shobaki

Hasan

Khasawinh

et al. 2000

Supercond. Sci. Technol.

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Hysteresis loop measurements of superconducting polycrystalline samples of Tl-2223 were carried out at various temperatures. Using the magnetization remanence (M R ) as measurement of the maximum vortex flux pinning at each temperature, our results reveal that the vortex flux pinning forces show two distinct behaviours of M R with temperature, a linear behaviour with t at high temperatures and an exponential behaviour with t β at low temperatures, where t = (1 − T /T c ) and β is constant of order 8. The effect of γ -irradiation shows six-fold enhancement in the vortex pinning over all temperatures up to T c . This increase in the pinning forces is attributed to the induced defects introduced by the γ -irradiation. The same enhancement in the pinning forces at all temperatures implies constant defects induced by γ -irradiation.

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“…A more direct alternative method is provided by measurements of the magnetization vector measurement M of a sample disc that is rotated about its axis in a fixed magnetic field H applied parallel to the disc plane. Our previous results in polycrystalline samples of YBCO and BKBO showed that in the rotational steady state, the vortex flux density B bifurcated into two distinct component: a rotational vortex flux component B R turns rigidly with the sample rotation and a frictional component B F stays at some frictional angle θ F relative to the field [4][5][6]. Our first aim in this work was to apply the same rotational experiment to new polycrystalline samples of Tl-2223 where one of them was γ -irradiated and to study their magnetic properties.…”

Section: Introductionmentioning

confidence: 93%

The rotational magnetic process and effects of gamma-irradiation on vortex flux pinning in Tl-2223 at low temperatures

Hasan¹,

Shobaki²,

Al‐Omari³

et al. 1999

Supercond. Sci. Technol.

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Magnetization vector measurements were carried out in a polycrystalline sample of Tl-2223 superconductor in fixed fields at low temperatures. Demonstrating the broad distribution in the vortex flux pinning, the vortex flux density B was seen to consist of two component: the rotational component BR turns rigidly with sample rotation and the frictional component BF stays at fixed angle F relative to the applied field H. The pinning torques per vortex were calculated as a function of H at constant temperature. The -irradiated sample shows an increase in pinning torque of ratio seven to one at temperatures 4.2 K and 25 K compared to an unirradiated sample; this is due to defects induced by the gamma irradiation.

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Rotational magnetic measurements of vortex pinning in polycrystalline type-II superconductors

Cited by 16 publications

References 17 publications

Irreversible magnetization in thin YBCO films rotated in external magnetic field

Irreversible magnetization in thin YBCO films rotated in external magnetic field

Temperature dependence of vortex flux pinning with γ-irradiation in polycrystalline Tl-2223

The rotational magnetic process and effects of gamma-irradiation on vortex flux pinning in Tl-2223 at low temperatures

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