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

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

This proposal is for the development of a high resolution, high sensitivity magnetic field imaging microscope. This instrument will allow for the measurement of minute magnetic fields (10-5 G) generated by currents in mesoscopic devices, the magnetic properties of quantum structures and the spin states of electrons inside devices. The instrument will be the first scanning Josephson junction microscope (SJM). It will have six orders of magnitude higher field sensitivity than conventional magnetic force microscopy and an order of magnitude better spatial resolution than scanning SQUID microscopy. In order to build this tool, the expertise of several groups at MIT must be brought together. The Josephson junction (JJ) that forms the critical sensing element must be integrated on an atomic force microscope tip in order to be in sufficient proximity to the sample. This process will require the development of a micromechanical silicon submount onto which the JJ will be processed. Once the sensing element has been fabricated it must be integrated into a larger instrument composed of cryogenically cooled piezo-stages and circuits to monitor and amplify the signals from the JJ. When completed, the combination of high field sensitivity and high spatial resolution will allow for the study of vortex states in superconductors, charge transport in circuits and biological systems, the magnetic state of mesoscopic magnets, and the spin state of electrons in devices. Finally, the development of a new scanning probe microscope offers exciting opportunities for interdisciplinary education. Already, students working on device processing, circuit design, mesoscopic device physics and materials science have all participated in the development of the core technologies.