A Procedure to Protect Granular and Porous Samples From Oxygen Contamination in High-Resolution Magnetization Measurements: Application to Granular High-T-c Cuprate Superconductors

作者：Ramos Alvarez A; Sonora D; Dancausa J D; Doval J M; Verde J C; Mosqueira J^*; Vidal F

来源：IEEE Transactions on Applied Superconductivity, 2016, 26(3): 7201103.

DOI：10.1109/TASC.2016.2529427

• Electromagnetic measurements
• granular superconductors
• high-temperature superconductors
• oxygen

Due to the paraantiferromagnetic transition of oxygen at 45 K, the contamination with this element may deeply affect measurements performed with high-resolution magnetometers around this temperature. We have studied this spurious effect by measuring with a commercial SQUID-based magnetometer (Quantum Design, model MPMS-XL) the magnetization of granular La1.85Sr0.15CuO4 (LSCO) superconductors by using different sample holders. Our results demonstrate the crucial role played by the O-2 physisorption in the extended surface of the LSCO grains, an effect that may be deeply mitigated by encapsulating the grains into an epoxy resin (EPO-TEK 301). This proceduremay be also useful for high-precision magnetization measurements at low temperatures in other granular or porous materials.

• 出版日期2016-4