Quantitative nanoscale vortex imaging using a cryogenic quantum magnetometer

Area of Science:

• Condensed Matter Physics
• Quantum Sensing
• Materials Science

Background:

• Microscopic studies of superconductors and their vortices are crucial for understanding superconductivity mechanisms.
• Existing experimental tools lack quantitative nanoscale magnetometry over wide temperature and magnetic field ranges.
• Local measurements of penetration depths and magnetic stray fields provide insights into superfluid densities and order parameter symmetry.

Purpose of the Study:

• To demonstrate a novel cryogenic scanning quantum sensor for nanoscale magnetic imaging of superconductors.
• To overcome limitations of existing experimental tools for quantitative magnetometry.
• To investigate Pearl vortices in cuprate superconductors with nanoscale precision.

Main Methods:

• Utilized a single nitrogen-vacancy (NV) electronic spin in diamond as a cryogenic scanning quantum sensor.
• Performed quantitative, nanoscale magnetic imaging of Pearl vortices in YBa2Cu3O7-δ.
• Employed a sensor-to-sample distance of approximately 10 nm.

Main Results:

• Observed striking deviations from the monopole approximation in vortex stray-field images.
• Achieved excellent quantitative agreement with Pearl's analytic model.
• Provided non-invasive and unambiguous determination of the local penetration depth.

Conclusions:

• The developed cryogenic quantum sensor overcomes existing limitations in nanoscale magnetometry.
• The sensor enables precise measurements of superconducting vortices and material properties.
• This technology opens new avenues for exploring strongly correlated electron physics and benchmarking microscopic models.