A signal input coil made of superconducting thin film for improved signal-to-noise ratio in a high-Tc SQUID-based ultra-low field nuclear magnetic resonance system

• Published in: Superconductor science & technology 2013-11, Vol.26 (11)
• Main Authors: Chen, Kuen-Lin, Hsu, Chin-Wei, Ku, Yue-Bai, Chen, Hsin-Hsien, Liao, Shu-Hsien, Wang, Li-Min, Horng, Herng-Er, Yang, Hong-Chang
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cuprates superconductors (high tc and insulating parent compounds); Exact sciences and technology; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Nuclear magnetic resonance and relaxation; Physics; Superconducting films and low-dimensional structures; Superconductivity
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/26/11/115008

Resonant coupling schemes are commonly used in SQUID-based ultra-low field (ULF) nuclear magnetic resonance (NMR) systems to couple the spin relaxation signals from samples to the SQUID. Generally, in NMR systems, a resonant coupling scheme is composed of two solenoid coils which are made of enamel insulated wires and a capacitor connected in series. In this work, we tried to replace the metal solenoid input coil with a planar high-Tc superconducting spiral coil to improve the signal-to-noise ratio (SNR) of the ULF NMR signal. A measurement of the free induction decay signal of water protons was performed to demonstrate the improved performance of the system. This improvement is due to the fact that the planar superconducting spiral coil possesses a higher mutual inductance with the SQUID. Therefore, it is a promising way to enhance the SNR of high-Tc SQUID-based ULF NMR/MRI systems.