Large Magnetoresistance at Room Temperature in Organic Molecular Tunnel Junctions with Nonmagnetic Electrodes

Zuoti Xie, Sha Shi, Feilong Liu, Darryl L. Smith, P. Paul Ruden, C. Daniel Frisbie

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

We report room-temperature resistance changes of up to 30% under weak magnetic fields (0.1 T) for molecular tunnel junctions composed of oligophenylene thiol molecules, 1-2 nm in length, sandwiched between gold contacts. The magnetoresistance (MR) is independent of field orientation and the length of the molecule; it appears to be an interface effect. Theoretical analysis suggests that the source of the MR is a two-carrier (two-hole) interaction at the interface, resulting in spin coupling between the tunneling hole and a localized hole at the Au/molecule contact. Such coupling leads to significantly different singlet and triplet transmission barriers at the interface. Even weak magnetic fields impede spin relaxation processes and thus modify the ratio of holes tunneling via the singlet state versus the triplet state, which leads to the large MR. Overall, the experiments and analysis suggest significant opportunities to explore large MR effects in molecular tunnel junctions based on widely available molecules.

Original languageEnglish (US)
Pages (from-to)8571-8577
Number of pages7
JournalACS nano
Volume10
Issue number9
DOIs
StatePublished - Sep 27 2016

Bibliographical note

Funding Information:
C.D.F. thanks NSF (CHE-1213876) for financial support.

Publisher Copyright:
© 2016 American Chemical Society.

Keywords

  • charge transport
  • interface dipole
  • magnetoresistance
  • singlet and triplet transmission
  • tunneling molecular junction
  • unpaired charge carrier

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