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Title: Scanning SQUID susceptometers with sub-micron spatial resolution

Abstract

Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ{sub 0}/Hz{sup 1/2}. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

Authors:
; ; ; ;  [1];  [2];  [3];  [4]; ;  [5]; ;  [6];  [7];  [5];  [8];  [9]
  1. Department of Applied Physics, Stanford University, Stanford, California 94305-4045 (United States)
  2. Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008-5252 (United States)
  3. Department of Physics, Stanford University, Stanford, California 94305-4045 (United States)
  4. Attocube Systems AG, Königinstraße 11A, 80539 Munich (Germany)
  5. Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States)
  6. IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)
  7. Department of Physics, University of Colorado Denver, Denver, Colorado 80217-3364 (United States)
  8. (United States)
  9. OcteVue, Hadley, Massachusetts 01035 (United States)
Publication Date:
OSTI Identifier:
22597627
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COMPARATIVE EVALUATIONS; DESIGN; FABRICATION; FEEDBACK; IMAGES; INTERFERENCE; MAGNETIC FIELDS; MAGNETIZATION; MICROSCOPY; SENSITIVITY; SENSORS; SIMULATION; SPATIAL RESOLUTION; SQUID DEVICES; SURFACES

Citation Formats

Kirtley, John R., E-mail: jkirtley@stanford.edu, Rosenberg, Aaron J., Palmstrom, Johanna C., Holland, Connor M., Moler, Kathryn A., Paulius, Lisa, Spanton, Eric M., Schiessl, Daniel, Jermain, Colin L., Gibbons, Jonathan, Fung, Y.-K.K., Gibson, Gerald W., Huber, Martin E., Ralph, Daniel C., Kavli Institute at Cornell, Ithaca, New York 14853, and Ketchen, Mark B. Scanning SQUID susceptometers with sub-micron spatial resolution. United States: N. p., 2016. Web. doi:10.1063/1.4961982.
Kirtley, John R., E-mail: jkirtley@stanford.edu, Rosenberg, Aaron J., Palmstrom, Johanna C., Holland, Connor M., Moler, Kathryn A., Paulius, Lisa, Spanton, Eric M., Schiessl, Daniel, Jermain, Colin L., Gibbons, Jonathan, Fung, Y.-K.K., Gibson, Gerald W., Huber, Martin E., Ralph, Daniel C., Kavli Institute at Cornell, Ithaca, New York 14853, & Ketchen, Mark B. Scanning SQUID susceptometers with sub-micron spatial resolution. United States. doi:10.1063/1.4961982.
Kirtley, John R., E-mail: jkirtley@stanford.edu, Rosenberg, Aaron J., Palmstrom, Johanna C., Holland, Connor M., Moler, Kathryn A., Paulius, Lisa, Spanton, Eric M., Schiessl, Daniel, Jermain, Colin L., Gibbons, Jonathan, Fung, Y.-K.K., Gibson, Gerald W., Huber, Martin E., Ralph, Daniel C., Kavli Institute at Cornell, Ithaca, New York 14853, and Ketchen, Mark B. 2016. "Scanning SQUID susceptometers with sub-micron spatial resolution". United States. doi:10.1063/1.4961982.
@article{osti_22597627,
title = {Scanning SQUID susceptometers with sub-micron spatial resolution},
author = {Kirtley, John R., E-mail: jkirtley@stanford.edu and Rosenberg, Aaron J. and Palmstrom, Johanna C. and Holland, Connor M. and Moler, Kathryn A. and Paulius, Lisa and Spanton, Eric M. and Schiessl, Daniel and Jermain, Colin L. and Gibbons, Jonathan and Fung, Y.-K.K. and Gibson, Gerald W. and Huber, Martin E. and Ralph, Daniel C. and Kavli Institute at Cornell, Ithaca, New York 14853 and Ketchen, Mark B.},
abstractNote = {Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ{sub 0}/Hz{sup 1/2}. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.},
doi = {10.1063/1.4961982},
journal = {Review of Scientific Instruments},
number = 9,
volume = 87,
place = {United States},
year = 2016,
month = 9
}
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