High temperature superconducting resonator for use in nuclear magnetic resonance microscopy

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 YBCO coil 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.