Field variation of the penetration depth in ceramicY1Ba2Cu3Oy

The high-frequency technique developed previously has been used to investigate the dependence of the penetration depth in superconducting tin on the strength of the applied field. A steady magnetic field was applied transverse to a thin cylindrical specimen forming part of a 3 cm. resonator, any resulting change in penetration depth being revealed as a shift in the resonant frequency. The change was greatest close to the transition temperature (3.72° K), but even here it amounted to no more than 3% at the critical field strength. As the temperature was lowered the effect became smaller at first, reaching a very low value at 3° K, and then increased once more to about 2 % at 1.7° K. The effect of a steady magnetic field on the high-frequency resistance was also studied, though not in great detail. Above 3° K the resistance decreases slightly until at a field strength rather greater than ½ H c a sudden increase announces the formation of the intermediate state. At lower temperatures the effect of the steady field is to increase the resistance slightly. It is suggested that the very small change in penetration depth even at the critical field strength is evidence of the existence of long-range order in the superconducting state over a distance of 10 -4 cm. or more, and the very sharp resistance transition in pure superconductors is adduced as further evidence of this hypothesis.

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On the Configuration of the Magnetic Field of β CrB

International Astronomical Union Colloquium ◽

10.1017/s0252921100080933 ◽

1976 ◽

Vol 32 ◽

pp. 613-622

Author(s):

I.A. Aslanov ◽

Yu.S. Rustamov

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Radial Velocity ◽

Magnetic Field Strength ◽

Complex Shape ◽

Rotation Period ◽

Field Variation ◽

Magnetic Field Variation ◽

Secular Variations ◽

The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

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The Sun as a Magnetic Star

International Astronomical Union Colloquium ◽

10.1017/s0252921100080775 ◽

1976 ◽

Vol 32 ◽

pp. 457-463

Author(s):

John M. Wilcox ◽

Leif Svalgaard

Keyword(s):

Recent Work ◽

Rotation Axis ◽

Polar Field ◽

Magnetic Star ◽

Rotational Axis ◽

Field Variation ◽

The Sun ◽

Arbitrary Angle ◽

Solar Magnetism ◽

Oblique Rotator

SummaryThe sun as a magnetic star is described on the basis of recent work on solar magnetism. Observations at an arbitrary angle to the rotation axis would show a 22-year polar field variation and a 25-day equatorial sector variation. The sector variation would be similar to an oblique rotator with an angle of 90° between the magnetic and rotational axis.

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