Magnetic tunnel junction sensors with conetic alloy

Z. Q. Lei, G. J. Li, William F. Egelhoff, P. T. Lai, Philip W.T. Pong

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Al2O3 magnetic tunneling junction (MTJ) sensors were fabricated with Conetic alloy Ni 77Fe 14Cu 5Mo 4 deposited as the free layer and pinned layer for its soft magnetic properties. It was observed that the Al2O 3 MTJ sensors with Conetic exhibited relatively small easy-axis coercivity. Tunneling magnetoresistance (TMR) and noise measurements were carried out to characterize the sensors. TMR of 9.5% and Hooge parameter of 3.825 × 10 -7μm2 were achieved without any hard-axis field. Hard-axis bias field was applied to eliminate the hysteresis and improve the linear field response of the MTJ sensor. The hysteresis was removed by applying an external magnetic field along the hard axis at 8 Oe and the sensor sensitivity was 0.4 %/Oe within a linear region at room temperature. The relationship between the Hooge parameter and hard-axis field was also investigated and the result demonstrated that the 1/f noise can be suppressed by an optimized hard-axis bias field. This work shows that it is feasible to use Conetic alloy as the soft magnetic layers in MTJ sensors for its small coercivity, and a hard-axis bias field can be used to linearize the sensor response and suppress the 1/f noise.

Original languageEnglish (US)
Article number5721853
Pages (from-to)714-717
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number3
StatePublished - Mar 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


  • 1/f Noise
  • Conetic
  • hard-axis bias field
  • magnetic sensor
  • magnetic tunnel junction (MTJ)


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