Fabrication and Characterization of Superconducting Probe Coil for High-Sensitivity NMR Spectroscopy

A solenoidal-shaped superconducting probe coil for taking NMR measurements was fabricated using Bi₂Sr₂CaCu₂O_x (Bi-2212), and then its quality factor was evaluated. The Bi-2212 probe coil was fabricated by dip-coating process. The quality factor values were Q = 5960-8820 (4.2 K, 0 T) in a frequency range of 400-600 MHz. These values were 2.3-2.5 times higher than those for a normal metal probe coil under the same measurement set up. In addition, the Bi-2212 probe coil maintained its superiority over a normal metal one even in a magnetic field up to 7 T. The measurement sensitivity of NMR depends on the quality factor of the probe coil. Therefore, the present experimental results obtained using the superconducting Bi-2212 probe coil are promising for taking high-sensitivity NMR measurements.