High frequency flux sampling SQUID microscope

ORAL

Abstract

One important application of scanning SQUID microscopes is to locate electrical faults in integrated circuits and multi-chip modules. However, current computer microprocessors operate at over 1 GHz, well above the bandwidth of the present generation of SQUID microscopes. By removing the conventional flux-locked loop electronics we have overcome the bandwidth limitations of traditional scanning SQUID microscopes. Instead we use a pulsed sampling technique with a small Nb/AlO$_{x}$/Nb hysteretic dc SQUID. We present time-varying magnetic field images of room temperature samples obtained with the SQUID mounted on a 4.2 K pulse tube refrigerator in a scanning SQUID microscope, and discuss the advantages and limitations of this method.

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Authors

  • Constantine Vlahacos

    CNAM, Department of Electrical and Computer Engineering, University of Maryland College Park and the Laboratory for Physical Sciences, University of Maryland

  • John Matthews

    Physical Optics Corporation

  • Frederick Wellstood

    Center for Nanophysics and Advanced Materials, Physics Department, University of Maryland College Park