Highly homogeneous MgB<sub>2</sub>films prepared by a new post-annealing process

Matveev, Andrei T.; Albrecht, J.; Konuma, M.; Stuhlhofer, Benjamin; Starke, U.; Habermeier, H.‐U.

doi:10.1088/0953-2048/18/10/010

Cited by 17 publications

(15 citation statements)

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“…The MgB 2 films were grown by sequential deposition of magnesium and boron layers using a conventional electron beam evaporation and a subsequent annealing process [15,16]. The films selected for this study had a lateral size of 5 5 mm 2 , a thickness of 200 nm, and the critical temperature of 35 K [17].…”

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“…Shown in the graph is the result of x-ray diffraction measurements obtained from surface reflection of a substrate mounted parallel to the φ-axis of a 4-circle diffractometer. The deviation θ of the direction of the The MgB 2 films were grown by sequential deposition of magnesium and boron layers using a conventional electron beam evaporation and a subsequent annealing process [15,16]. The films selected for this study had a lateral size of 5 × 5 mm 2 and a thickness of 200 nm.…”

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Dramatic Role of Critical Current Anisotropy on Flux Avalanches inMgB2Films

Albrecht¹,

Matveev²,

Strempfer

et al. 2007

Phys. Rev. Lett.

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Anisotropic penetration of magnetic flux in MgB(2) films grown on vicinal sapphire substrates is investigated using magneto-optical imaging. Regular penetration above 10 K proceeds more easily along the substrate surface steps, the anisotropy of the critical current being 6%. At lower temperatures the penetration occurs via abrupt dendritic avalanches that preferentially propagate perpendicular to the surface steps. This inverse anisotropy in the penetration pattern becomes dramatic very close to 10 K where all flux avalanches propagate in the strongest pinning direction. The observed behavior is fully explained using a thermomagnetic model of the dendritic instability.

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Dramatic Role of Critical Current Anisotropy on Flux Avalanches inMgB2Films

Albrecht¹,

Matveev²,

Strempfer

et al. 2007

Phys. Rev. Lett.

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“…10,11 These films with a lateral size of 5 ϫ 5 mm 2 and a thickness of 100-200 nm are partly covered with 1 m of gold by a standard thermal evaporation technique using metal masks. The main goal was the creation of borders between covered and noncovered regions with different angles of incidence of the propagating avalanches.…”

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Bending of magnetic avalanches in MgB2 thin films

Albrecht¹,

Matveev²,

Djupmyr³

et al. 2005

Applied Physics Letters

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The penetration of magnetic flux into a superconductor above the lower critical field does not necessarily happen in a regular way. It is found that under particular conditions, a chaotic penetration in form of magnetic avalanches occurs. These avalanches are closely related to the so-called thermomagnetic instability, which identifies local heating due to flux line movement as the origin of the effect. In case of MgB2 thin films, these avalanches are found only below T=10K and are suppressed by a covering metallic layer with high thermal conductivity and sufficient thickness. These avalanches are observed in the case of partly gold covered MgB2 films by the magneto-optical Faraday effect. The investigation of avalanches propagating into a gold-covered region revealed a change of the propagation direction depending on the incident angle of these avalanches.

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“…Fitting the data has been done using Eq. (6). The resulting parameters are m 0 = 0.11942 emu, t 0 = 3.38 s and n = 160, respectively.…”

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“…For details see Refs. [6,7]. These films are approximately 300 nm thick and have lateral dimensions of 5 Â 5 mm 2 .…”

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confidence: 99%