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Sensitive Single-Level Magnetometers of High Tc dc SQUIDS
WANG Shiguang, DAI Yuandong, ZENG Xianghui, ZHENG Peihui,
WANG Shouzheng, XIONG Guangcheng, LIAN Guijun, GAN Zizhao
Chin. Phys. Lett. 1995, 12 (4):
229-232
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We have developed a simple sintering system to prepare the yttria-stabilized-zirconia (YSZ) bicrystals. Grain-boundary junctions made from the epitaxial YBa2Cu3O7-δ films on the bicrystal substrates demonstrated Josephson behavior. Using new square washer design, single-level magnetometer of dc superconducting quantum interference. device (SQUID) has been fabricated. Owing to the flux focusing effect of the large washer, the magnetic field sensitivity of the devices has been enhanced. The magnetic field resolution of the magnetometer is IpT/Hz1/2 at 10Hz, and increases to 3pT/Hz1/2 at 1Hz at 77K.
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Flux Creep Determination of Field Dependence of Magnetic Jc at Low Temperatures
RUI Ying, JI Helin, XU Xiaonong, QIN Mengjun, SHAO Huimin, JIN Xin, YAO Xixian
Chin. Phys. Lett. 1995, 12 (4):
233-236
.
The effective activation energy of one HgBaCaCuO 1223 superconductor as a function of current density was extracted from the magnetic relaxation measurements below 30K, and found to obey a power law. We also obtained effective activation energy as a function of current density from the magnetic hysteresis loops (M-H). The data sets for the M-H loops at different temperatures overlap each other, and all fall on the smooth Ueff( J,0 ) curve based solely on the magnetization relaxation measurements. This indicates that the field dependence of magnetic critical current density is determined by the flux creep via nonlinear effective activation energy at low temperatures.
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17 articles
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