Direct Measurement of spin polarization in ferromagnetic-C60 interfaces using point-contact andreev reflection

Fatma Al Ma'Mari, May Wheeler, Ellen Kendric, Gavin Burnell, Brian J. Hickey, Tim Moorsom, Oscar Cespedes

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

An important step has been developed combining the potential of spintronics with organic electronics to reveal the promising field of molecular spintronics, which can offer more flexibility, higher recyclability, and low-production costs compared with inorganic devices. Room temperature magnetoresistance (MR) of 5% has been obtained from C60 spin valves with the structure Co(20 nm)/Al2 O3(1.2 nm)/C60 (5-60 nm)/Py(20 nm)/Al(1.5 nm). We observe an asymmetric dependence at low temperatures of the MR with voltage, and surprisingly with the magnetic field as well. This behavior has been attributed to the organic interface formed at the junction, which results in a change of the ferromagnet's spin polarization. The spin polarization at the organic-ferromagnetic interface is extracted by measuring the bias dependence of the conductance of a metallic-superconducting point contact and analyzed the spectra with the modified Blonder-Tinkham-Klapwijk theory. Point-contact Andreev reflection measurements reveal that the Co-C60 possess spin polarization of 30% ± 1%, compared with 40% ± 1% for our Co films without C60. This could account for the asymmetry of the MR in spin valves incorporating C60 and the need for an alumina spacer to maximize the MR.

Original languageEnglish
Article number6971749
JournalIEEE Transactions on Magnetics
Volume50
Issue number11
DOIs
Publication statusPublished - Nov 1 2014

Keywords

  • C
  • magnetoresistance (MR)
  • organic spintronics
  • point-contact Andreev reflection (PCAR).

ASJC Scopus subject areas

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

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