Critical challenges for picoTesla magnetic-tunnel-junction sensors

W. F. Egelhoff, P. W.T. Pong, J. Unguris, R. D. McMichael, E. R. Nowak, A. S. Edelstein, J. E. Burnette, G. A. Fischer

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

The extension of small, inexpensive, low-power, low-frequency, ultra-sensitive magnetic sensors to fields between 1 nT and 1 pT, an area currently dominated by fluxgates, optically pumped magnetometers, and SQUIDS, would be a paradigm shift for the field of magnetic sensors. The necessary elements for picoTesla magnetic-tunnel-junction (MTJ) sensors have been identified by modeling the noise characteristics. The results help identify the experimental challenges involved in the integration of these necessary elements into actual sensors, illustrate the trade-offs faced if there are losses in performance upon integration. Scanning electron microscopy with polarization analysis (SEMPA) of the pinned layer provides insights into problems and possible solutions. Issues associated with real-world applications of these sensors to ultra-low field measurements are discussed.

Original languageEnglish (US)
Pages (from-to)217-225
Number of pages9
JournalSensors and Actuators, A: Physical
Volume155
Issue number2
DOIs
StatePublished - Oct 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering

Keywords

  • Magnetic sensors
  • Magnetic-tunnel-junction
  • Tunneling magnetoresistance
  • picoTesla

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