High temperature superconducting resonator for use in nuclear magnetic resonance microscopy

Abstract
We describe surface coil resonators made with thin‐film Y1Ba2Cu3O7(YBCO) for use in high‐resolution nuclear magnetic resonance imaging. At the operating temperature of the coil, 10 K, we have measured Q values (quality factor) in excess of 50 000 at 300 MHz in magnetic fields as high as 9 T. Noise temperature measurements of this superconducting probe indicate that the dominant noise source is Johnson noise. We describe a coupling circuit comprised of the YBCOcoil that is inductively coupled to a room‐temperature copper resonator. This circuit preserves the high signal‐to‐noise ratio that accrues to the YBCO resonator.