LTS SQUID-Microscopy: A Leap in Sensitivity?

Franz Baudenbacher, Vanderbilt University, Nashville, TN

Room-temperature (RT) sample scanning superconducting quantum interference device (SQUID) microscopy (SSM) is a very powerful and promising technique for imaging magnetic field distributions. In contrast to conventional instrumentation SQUID microscopy promises a leap in sensitivity but different SQUID sensor designs and configurations are necessary to achieve the best combination of spatial resolution and field sensitivity for a given application and source configuration. Therefore, we have developed a scanning superconducting quantum interference device (SQUID) microscope system with interchangeable sensor configurations for imaging magnetic fields of room-temperature (RT) samples with sub-millimeter resolution. The sensors are mounted in the vacuum space of a cryostat and thermally anchored to the helium reservoir. A 25 mm sapphire window separates the vacuum space from the RT sample. A positioning mechanism allows us to adjust the sample-to-sensor spacing from the top of the Dewar. We achieved a sensor-to-sample spacing of 100 mm, which could be maintained for periods of up to 4 weeks.

In this talk I will discuss the detection of single ferromagnetic particles that flow at room temperature in a microfluidic channel located close to the SQUID sensor. In addition, the same SQUID microscope has been used to image action current distributions in isolated rabbit hearts.

The P/T Colloquium is
typically held each
Thursday, 3:45–5:00 PM.

Collaborations and Refreshments, 3:15 PM.