Preparation and Measurement

A multiloop dc SQUID from 2 YBCO layers and an intermediate STO insulation layer. The diameter is 7 mm. The smallest structures on this chip are 3 µm wide.
A multiloop dc SQUID from 2 YBCO layers and an intermediate STO insulation layer. The diameter is 7 mm. The smallest structures on this chip are 3 µm wide.

The multilayer magnetometers described here are based on two superconducting YBa2Cu3O7 layers and an intermediate SrTiO3 layer for their insulation. Both types of thin-films are deposited by off-axis rf magnetron sputtering in an Ar/O2 atmosphere. The patterning of the thin-films is done by conventional photolithography and Ar-ion beam etching. Single layer magnetometers have also been prepared by a pulsed laser deposition process using a 248 nm KrF Excimer laser.

Multilayer Technology

SEM micrograph of the central part of a multi loop magnetometer in multilayer technology.
SEM micrograph of the central part of a multi loop magnetometer in multilayer technology.

Pulsed Laser Deposition

Laser ablation plume while depositing a YBCO thin-film.
Laser ablation plume while depositing a YBCO thin-film.

Oxygen Plasma Treatment

Barrel chamber for oxygen plasma treatment of YBCO thin-films.
Barrel chamber for oxygen plasma treatment of YBCO thin-films.

Measurement and characterization

  1. The measurement setup.
    The measurement setup.

    Multimeter,

  2. SQUID FLL electronics,
  3. Temperature controller,
  4. Waveform generator,
  5. Oscilloscope,
  6. FFT signal analyzer,
  7. Lock-in amplifier,
  8. Multi purpose data acquisition unit,
  9. Lead acid battery chargers,
  10. Battery powered modular SQUID electronics,
  11. Probe holder,
  12. Apple Power Macintosh,
  13. Liquid nitrogen dewar.

All instruments are connected via GPIB Bus to an Apple Power Macintosh (More details).

FFT analyzer and SQUID FLL electronics.
FFT analyzer and SQUID FLL electronics.