| The design and operation of a new magnetic imaging system based on a scanning magnetoresistive probe with high spatial resolution is discussed. The ability of this system to image current densities at sub-micron length scales is demonstrated. To obtain current density information, a deconvolution algorithm has been developed. We will discuss the advantages and drawbacks of our method, as well as tradeoffs inherent in the design of the system.; This technique has spawned a new, non-invasive method for conducting research in a number of fields of condensed matter physics. We have applied the tool to the imaging of current density evolution in systems undergoing electromigration damage. In addition, we have imaged current flow in a wide variety of integrated circuits for the purposes of failure analysis and fault isolation. This instrument has provided direct imaging of dielectric breakdown and pinhole formation in ultra-thin insulating layers of operating magnetic tunnel junction (MTJ) devices for the first time. Finally, the potential of this method for investigation of micron-scale patterned magnetic elements is explored.; In addition, we have explored magnetic coupling and micromagnetic phenomena in mesoscopic magnetic systems via transport measurements of MTJs in two-dimensional applied fields. These results will be analyzed using the Stoner-Wohlfarth single-domain model as a starting point. Interfacial roughness properties at the tunnel barrier have also been characterized using a variety of methods. |
