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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 at 0.1 µV/cm versus magnetic field for the Bi-2212 specimen for various field-sweep directions, temperatures, and angles: (a) 4 K and 90°, (b) 20 K and 90°, (c) 35 K and 90°, (d) 4 K and 0°, (e) 20 K and 0°, (f) 35 K and 0°.
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f11-j64goo: Ic at 0.1 µV/cm versus magnetic field for the Bi-2212 specimen for various field-sweep directions, temperatures, and angles: (a) 4 K and 90°, (b) 20 K and 90°, (c) 35 K and 90°, (d) 4 K and 0°, (e) 20 K and 0°, (f) 35 K and 0°.

Mentions: Field-sweep hysteresis on the Bi-2212 specimen is shown in Fig. 11a at 4 K and 90°. The largest difference in measured Ic occurs at about 3 T and is about 6 %. This is much less than the 40 % hysteresis observed in the Bi-2223 specimen at 4 K and 90°. For the Bi-2212 specimen, the largest difference between the first up and the second up is about 1 %. The difference between zero-field values is about 1.4 %.


Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors
Ic at 0.1 µV/cm versus magnetic field for the Bi-2212 specimen for various field-sweep directions, temperatures, and angles: (a) 4 K and 90°, (b) 20 K and 90°, (c) 35 K and 90°, (d) 4 K and 0°, (e) 20 K and 0°, (f) 35 K and 0°.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f11-j64goo: Ic at 0.1 µV/cm versus magnetic field for the Bi-2212 specimen for various field-sweep directions, temperatures, and angles: (a) 4 K and 90°, (b) 20 K and 90°, (c) 35 K and 90°, (d) 4 K and 0°, (e) 20 K and 0°, (f) 35 K and 0°.
Mentions: Field-sweep hysteresis on the Bi-2212 specimen is shown in Fig. 11a at 4 K and 90°. The largest difference in measured Ic occurs at about 3 T and is about 6 %. This is much less than the 40 % hysteresis observed in the Bi-2223 specimen at 4 K and 90°. For the Bi-2212 specimen, the largest difference between the first up and the second up is about 1 %. The difference between zero-field values is about 1.4 %.

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.