Large Magnetoresistance in Single-Radical Molecular Junctions

Organic radicals are promising building blocks for molecular spintronics. Little is known about the role of unpaired electrons for electron transport at the single-molecule level. Here, we examine the impact of magnetic fields on electron transport in single oligo(p-phenyleneethynylene) (OPE)-based radical molecular junctions, which are formed with a mechanically controllable break-junction technique at a low temperature of 4.2 K. Surprisingly huge positive magnetoresistances (MRs) of 16 to 287% are visible for a magnetic field of 4 T, and the values are at least 1 order of magnitude larger than those of the analogous pristine OPE (2-4%). Rigorous analysis of the MR and of current-voltage and inelastic electron-tunneling spectroscopy measurements reveal an effective reduction of the electronic coupling between the current-carrying molecular orbital and the electrodes with increasing magnetic field. We suggest that the large MR for the single-radical molecular junctions might be ascribed to a loss of phase coherence of the charge carriers induced by the magnetic field. Although further investigations are required to reveal the mechanism underlying the strong MR, our findings provide a potential approach for tuning charge transport in metal-molecule junctions with organic radicals.

Subject (DDC)

530 Physics

Keywords

Single organic radicals, large magnetoresistance, charge transport, mechanically controllable break junction

Cite This

ISO 690

HAYAKAWA, Ryoma, Mohammad Amin KARIMI, Jannic WOLF, Thomas HUHN, Martin Sebastian ZÖLLNER, Carmen HERRMANN, Elke SCHEER, 2016. Large Magnetoresistance in Single-Radical Molecular Junctions. In: Nano Letters. 16(8), pp. 4960-4967. ISSN 1530-6984. eISSN 1530-6992. Available under: doi: 10.1021/acs.nanolett.6b01595

BibTex

@article{Hayakawa2016-08-10Large-35186,
  year={2016},
  doi={10.1021/acs.nanolett.6b01595},
  title={Large Magnetoresistance in Single-Radical Molecular Junctions},
  number={8},
  volume={16},
  issn={1530-6984},
  journal={Nano Letters},
  pages={4960--4967},
  author={Hayakawa, Ryoma and Karimi, Mohammad Amin and Wolf, Jannic and Huhn, Thomas and Zöllner, Martin Sebastian and Herrmann, Carmen and Scheer, Elke}
}

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Bibliography of Konstanz

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