Responses of High Tc Superconductors to Various Combinations of AC and DC Magnetic Fields
In the study of classical as well as high Tc superconductors, magnetic measurements are often used.1–4 In these experiments, the response of the sample to an applied magnetic field with the magnitude constant or changing in time is observed. In the former case one speaks about a DC measurement while in the later about an AC measurement, respectively. Sometimes the combination of AC and DC fields can be very helpful, too. Because it is common practice to use different terminology in reporting results of such experiments, we will define the basic terms used in what follows. First of all, to avoid problems caused only by the irregular shape of the sample, we consider a slim cylinder with a height much greater than its radius R, placed in a homogeneous magnetic field Bext parallel to the axis. In this case the field acting on the sample is equal to Bext. However, one should not neglect the fact that the magnetization inside the superconducting sample is in general not homogeneous.
KeywordsCritical Current Density Magnetization Loop Phase Sensitive Detector Irreversibility Line Magnetic Field Profile
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