Development of: High Resolution, High Sensitivity Scanning Josephson Junction Microscope

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This proposal is for the development of a high resolution, high sensitivitymagnetic field imaging microscope. This instrument will allow for themeasurement of minute magnetic fields (10-5 G) generated by currents inmesoscopic devices, the magnetic properties of quantum structures and thespin states of electrons inside devices. The instrument will be the firstscanning Josephson junction microscope (SJM). It will have six orders ofmagnitude higher field sensitivity than conventional magnetic forcemicroscopy and an order of magnitude better spatial resolution thanscanning SQUID microscopy.In order to build this tool, the expertise of several groups at MIT must bebrought together. The Josephson junction (JJ) that forms the criticalsensing element must be integrated on an atomic force microscope tip inorder to be in sufficient proximity to the sample. This process willrequire the development of a micromechanical silicon submount onto whichthe JJ will be processed. Once the sensing element has been fabricated itmust be integrated into a larger instrument composed of cryogenicallycooled piezo-stages and circuits to monitor and amplify the signals fromthe JJ. When completed, the combination of high field sensitivity andhigh spatial resolution will allow for the study of vortex states insuperconductors, charge transport in circuits and biological systems, themagnetic state of mesoscopic magnets, and the spin state of electrons indevices.Finally, the development of a new scanning probe microscope offers excitingopportunities for interdisciplinary education. Already, students workingon device processing, circuit design, mesoscopic device physics andmaterials science have all participated in the development of the coretechnologies.