Materials Research Express (Jan 2020)

Magnetoresistance effect in a vertical spin valve fabricated with a dry-transferred CVD graphene and a resist-free process

  • Pradeep Raj Sharma,
  • Praveen Gautam,
  • Jungtae Nam,
  • Keun Soo Kim,
  • Hwayong Noh

DOI
https://doi.org/10.1088/2053-1591/abad03
Journal volume & issue
Vol. 7, no. 8
p. 085603

Abstract

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One of the most prominent and effective applications of graphene in the field of spintronics is its use as a spacer layer between ferromagnetic metals in vertical spin valve devices, which are widely used as magnetic sensors. The magnetoresistance in such devices can be enhanced by a selection of suitable spacer materials and proper fabrication procedures. Here, we report the use of dry-transferred single- and double-layer graphene, grown by chemical vapor deposition (CVD), as the spacer layer and the fabrication procedure in which no photo-resist or electron-beam resists is used. The measured maximum magnetoresistance of NiFe/CVD-Graphene/Co junction is 0.9% for the single- and 1.2% for the double-layer graphene at 30 K. The spin polarization efficiency of the ferromagnetic electrodes is about 6.7% and 8% for the single- and the double-layer graphene, respectively, at the same temperature. The bias-independent magnetoresistance rules out any contamination and oxidation of the interfaces between the ferromagnet and the graphene. The magnetoresistance measured as a function of tilted magnetic field at different angles showed no changes in the maximum value, which implies that the magnetoresistance signal is absent from anisotropic effects.

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