Superconductive quantum interference magnetometer with high sensitivity achieved by an induced resonance.

Area of Science:

• Superconducting quantum devices
• Magnetometry
• Low-noise electronics

Background:

• Superconducting Quantum Interference Devices (SQUIDs) are sensitive magnetic flux detectors.
• Achieving high voltage responsivity and low magnetic noise is crucial for advanced applications.
• Existing SQUID magnetometers face limitations in sensitivity and operational characteristics.

Purpose of the Study:

• To develop a fully integrated, low-noise SQUID magnetometer with enhanced voltage responsivity.
• To investigate the effect of an integrated superconducting coil on SQUID performance.
• To evaluate the suitability of the developed magnetometer for practical applications.

Main Methods:

• Fabrication of a fully integrated SQUID magnetometer.
• Introduction of resonance via an integrated superconducting coil to enhance voltage responsivity.
• Measurement of voltage-magnetic flux characteristics, magnetic field noise spectral density, bandwidth, and slew rate.

Main Results:

• Achieved intrinsic voltage responsivity as high as 500 μV/Φ0.
• Demonstrated a spectral density of magnetic field noise as low as 3 fT/Hz(1/2).
• Characterized bandwidth and slew rate, comparing with and without resonance and positive feedback.

Conclusions:

• The integrated resonance technique significantly enhances SQUID voltage responsivity.
• The developed SQUID magnetometer exhibits excellent low-noise characteristics.
• The device's performance makes it suitable for various applications, including biomagnetism.