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Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors

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ABSTRACT

We have investigated magnetic hysteresis in transport critical-current (Ic) measurements of Ag-matrix (Bi,Pb)2Sr2Ca2Cu3O10–x (Bi-2223) and AgMg-matrix Bi2Sr2CaCu2O8+x (Bi-2212) tapes. The effect of magnetic hysteresis on the measured critical current of high temperature superconductors is a very important consideration for every measurement procedure that involves more than one sweep of magnetic field, changes in field angle, or changes in temperature at a given field. The existence of this hysteresis is well known; however, the implications for a measurement standard or interlaboratory comparisons are often ignored and the measurements are often made in the most expedient way. A key finding is that Ic at a given angle, determined by sweeping the angles in a given magnetic field, can be 17 % different from the Ic determined after the angle was fixed in zero field and the magnet then ramped to the given field. Which value is correct is addressed in the context that the proper sequence of measurement conditions reflects the application conditions. The hysteresis in angle-sweep and temperature-sweep data is related to the hysteresis observed when the field is swept up and down at constant angle and temperature. The necessity of heating a specimen to near its transition temperature to reset it to an initial state between measurements at different angles and temperatures is discussed.

No MeSH data available.


Ic(H down)/Ic(H up) versus magnetic field for the Bi-2223 specimen for various angles, criteria, and temperatures: (a) 50 K, (b) 65 K, (c) 80 K.
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f9-j64goo: Ic(H down)/Ic(H up) versus magnetic field for the Bi-2223 specimen for various angles, criteria, and temperatures: (a) 50 K, (b) 65 K, (c) 80 K.

Mentions: Another way to show the field-sweep hysteresis is to plot the ratio of Ic measured with decreasing field to that measured with increasing field, Ic(H down)/Ic(H up), versus magnetic field. Such plots are shown in Figs. 8 and 9 at temperatures of 4 K, 10 K, 20 K, 35 K, 50 K, 65 K, and 80 K. In each plot, curves are shown for 0° and 90° and for 0.1 µV/cm and 1.0 µV/cm. The curves differ very little at different criteria. The anomalous ratios at the higher fields and temperatures (see Fig. 9b, 0°) are due to slight differences in the small Ic values. The size and field dependence of the hysteresis is illustrated in these curves.


Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors
Ic(H down)/Ic(H up) versus magnetic field for the Bi-2223 specimen for various angles, criteria, and temperatures: (a) 50 K, (b) 65 K, (c) 80 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862823&req=5

f9-j64goo: Ic(H down)/Ic(H up) versus magnetic field for the Bi-2223 specimen for various angles, criteria, and temperatures: (a) 50 K, (b) 65 K, (c) 80 K.
Mentions: Another way to show the field-sweep hysteresis is to plot the ratio of Ic measured with decreasing field to that measured with increasing field, Ic(H down)/Ic(H up), versus magnetic field. Such plots are shown in Figs. 8 and 9 at temperatures of 4 K, 10 K, 20 K, 35 K, 50 K, 65 K, and 80 K. In each plot, curves are shown for 0° and 90° and for 0.1 µV/cm and 1.0 µV/cm. The curves differ very little at different criteria. The anomalous ratios at the higher fields and temperatures (see Fig. 9b, 0°) are due to slight differences in the small Ic values. The size and field dependence of the hysteresis is illustrated in these curves.

View Article: PubMed Central - PubMed

ABSTRACT

We have investigated magnetic hysteresis in transport critical-current (Ic) measurements of Ag-matrix (Bi,Pb)2Sr2Ca2Cu3O10–x (Bi-2223) and AgMg-matrix Bi2Sr2CaCu2O8+x (Bi-2212) tapes. The effect of magnetic hysteresis on the measured critical current of high temperature superconductors is a very important consideration for every measurement procedure that involves more than one sweep of magnetic field, changes in field angle, or changes in temperature at a given field. The existence of this hysteresis is well known; however, the implications for a measurement standard or interlaboratory comparisons are often ignored and the measurements are often made in the most expedient way. A key finding is that Ic at a given angle, determined by sweeping the angles in a given magnetic field, can be 17 % different from the Ic determined after the angle was fixed in zero field and the magnet then ramped to the given field. Which value is correct is addressed in the context that the proper sequence of measurement conditions reflects the application conditions. The hysteresis in angle-sweep and temperature-sweep data is related to the hysteresis observed when the field is swept up and down at constant angle and temperature. The necessity of heating a specimen to near its transition temperature to reset it to an initial state between measurements at different angles and temperatures is discussed.

No MeSH data available.