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Tunable magnetoresistance in an asymmetrically coupled single-molecule junction
Ben Warner1, Fadi El Hallak2, Henning Prüser2
11] London Centre for Nanotechnology, University College London (UCL), London WC1H 0AH, UK [2] Department of Physics &Astronomy, UCL, London WC1E 6BT, UK.
Nature Nanotechnology
|January 27, 2015
Summary
Researchers observed significant magnetic field sensitivity in single-molecule junctions. This discovery paves the way for advanced molecular spintronic devices and sensors utilizing negative differential resistance.
Area of Science:
- Molecular spintronics
- Quantum transport
- Surface science
Background:
- Magnetic field sensitivity is crucial for sensors and memory devices.
- Scaling spintronic phenomena to the single-molecule level promises novel device applications.
Purpose of the Study:
- To report and characterize magnetoresistance in a single-molecule junction.
- To investigate the underlying mechanisms of magnetic field sensitivity at the molecular level.
Main Methods:
- Fabrication of a single-molecule junction using iron phthalocyanine (FePc) on a copper nitride (Cu2N) layer on a Cu(001) surface.
- Measurement of magnetoresistance and negative differential resistance (NDR) under varying magnetic fields and applied bias.
- Analysis of electron transport through molecular states and their coupling to electrodes.
Main Results:
- Observed magnetoresistance in a single-molecule junction with a magnetic field sensitivity significantly exceeding Zeeman shifts.
- Identified two voltage-tunable forms of magnetoresistance controlled by applied bias.
- Attributed NDR to transient charging of the FePc molecule and alignment of molecular states with the Fermi energy.
- Demonstrated an asymmetric voltage-divider effect enhancing the apparent magnetic field shift.
Conclusions:
- Asymmetric coupling to metallic electrodes significantly impacts molecular transport.
- This coupling can be leveraged for developing molecular spintronic applications.
- The observed phenomenon offers a pathway for highly sensitive magnetic field sensors and non-volatile memory at the molecular scale.
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