Imaging of current density distributions with a Nb weak-link scanning nano-SQUID microscope

Area of Science:

• Condensed Matter Physics
• Nanotechnology
• Quantum Sensing

Background:

• Superconducting Quantum Interference Devices (SQUIDs) offer unparalleled magnetic field sensitivity.
• Imaging local magnetic fields is crucial for understanding spin properties and current distributions in 2D materials.
• Miniaturized nano-SQUIDs are essential for high-resolution nanoscale measurements.

Purpose of the Study:

• To develop a weak-link nano-SQUID scanning microscope with reduced hysteresis in current-voltage characteristics.
• To enable high-resolution imaging of magnetic fields in nanometer-scale samples.
• To reconstruct two-dimensional current density vector distributions.

Main Methods:

• Fabrication of weak-link Dayem Josephson junction nano-SQUIDs.
• Development of a scanning microscope utilizing these nano-SQUIDs.
• Measurement of magnetic fields and reconstruction of current density vectors.

Main Results:

• Successful development of a nano-SQUID scanning microscope with significantly reduced hysteresis.
• Demonstration of high-spatial-resolution magnetic field imaging capabilities.
• Accurate reconstruction of two-dimensional current density vectors in a two-dimensional electron gas.

Conclusions:

• The developed nano-SQUID scanning microscope overcomes hysteresis limitations of previous designs.
• This technology enables advanced nanoscale characterization of electronic properties in 2D materials.
• The technique provides a powerful tool for exploring quantum phenomena in condensed matter systems.