An integrated superconductive magnetic nanosensor for high-sensitivity nanoscale applications

Area of Science:

• Condensed Matter Physics
• Nanotechnology
• Quantum Technologies

Background:

• Development of ultrasensitive magnetic sensors is crucial for nanoscale characterization.
• Superconducting Quantum Interference Devices (SQUIDs) offer high magnetic field sensitivity.
• Miniaturization of SQUIDs to the nanoscale is essential for advanced applications.

Purpose of the Study:

• To present an integrated magnetic nanosensor based on a niobium dc SQUID.
• To characterize the performance of the nanosensor for nanoscale applications.
• To explore potential applications in magnetic detection and quantum computing.

Main Methods:

• Fabrication of a washer-shaped niobium dc SQUID with nanobridges using electron beam lithography, lift-off, and reactive ion etching.
• Integration of on-chip niobium coils for sensor excitation and flux biasing.
• Characterization of voltage-flux characteristics and noise performance at liquid helium temperature.

Main Results:

• Achieved a voltage swing of 75 µV and a maximum voltage-flux transfer coefficient (responsivity) of 1 mV/Φ(0).
• Demonstrated a white magnetic flux noise spectral density as low as 2.5 μΦ(0) Hz(-1/2).
• Attained a spin sensitivity of 100 spin Hz(-1/2) in units of the Bohr magneton.

Conclusions:

• The developed niobium dc SQUID nanosensor is a highly sensitive platform for nanoscale magnetic measurements.
• Its performance metrics suggest suitability for detecting nanoparticles, molecular clusters, and nanoobject magnetization.
• The nanosensor holds promise for applications in advanced magnetic sensing and quantum computing.