Nano Superconducting QUantum Interference Device sensors for magnetic nanoparticle detection.

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Superconducting QUantum Interference Devices (SQUIDs) are sensitive magnetic flux detectors.
• Niobium (Nb) nanobridge Josephson junctions offer potential for advanced SQUID fabrication.
• Characterizing SQUID performance and exploring novel applications are ongoing research areas.

Purpose of the Study:

• To describe the fabrication and characterization of Superconducting QUantum Interference Devices (SQUIDs) based on single-layer niobium (Nb) nanobridge Josephson junctions.
• To evaluate the responsivity and performance of these SQUIDs.
• To demonstrate the preliminary detection capability of SQUIDs for silica-magnetite nanoparticles.

Main Methods:

• Fabrication of SQUID devices with loop areas from 4 to 0.5 microm2 using Electron Beam Lithography (EBL) on a 20 nm thick Nb layer.
• Magnetization measurements conducted via switching current measurements at a cryogenic temperature (T = 4.2 K).

Main Results:

• SQUID devices with responsivity up to 30 microA/phi0 were achieved.
• Successful preliminary detection of silica-magnetite (Fe3O4-SiO2) core/shell nanoparticle clusters was demonstrated.

Conclusions:

• Single-layer Nb nanobridge Josephson junction SQUIDs are viable for sensitive magnetic measurements.
• These SQUIDs show promise for detecting nanoscale magnetic materials like silica-magnetite nanoparticles.