BGU Physics Department

Colloquium, Dec. 5th, 2013

Sensors for scanning SQUID microscopy approaching and surpassing single electron spin sensitivity

Martin E. Huber, Department of Physics, University of Colorado Denver (Visiting Fulbright Scholar)

Superconducting quantum interference devices (SQUIDs) are among the most sensitive sensors for magnetic field, and nanoscale SQUIDs, in particular, also have high sensitivity to magnetic dipole fields. The sensitivity of SQUIDs with submicron sensor areas is better than ~100 ÁB/√Hz, where ÁB is the Bohr magneton, the magnetic dipole moment of the electron. When coupled with a scanning platform, these nanoscale SQUIDs become powerful tools for studying properties of magnetic systems, including persistent currents in normal metal rings, local measurements of penetration depths in high Tc superconductors, vortex dynamics in type II superconductors, and imaging edge currents in topological insulators. I will describe two such nanoscale SQUID sensors, planar SQUID susceptometers with sensitivities of ~70 ÁB/√Hz and needle-like SQUID magnetometers with sensitivities better than 1 ÁB/√Hz, concluding with recent results of, and future plans for, studies using these sensors.