What is it about?

Molecular bridges covalently bonded to two ferromagnetic electrodes can transform ferromagnetic materials and produce intriguing spin transport characteristics. Previously, we theoretically and experimentally studied the impact of paramagnetic molecules on the magnetic properties of the magnetic tunnel junctions (Tyagi et al. Nanotechnology, Vol.26, p.305602, 2015). In this follow up the paper we have investigated the impact of previously demonstrated molecule induced strong coupling on spin transport. To study the molecular coupling effect experimentally we attached paramagnetic molecules between two ferromagnetic electrodes of a magnetic tunnel junction along the exposed side edges. The strong molecule coupling between two ferromagnetic electrodes caused drastic changes in the transport properties of the magnetic tunnel junction testbed. Molecular transport channels along the tunnel junction edges decreased the tunneling current as compared to the leakage current of the bare tunnel junction at room temperature. The current magnitude on the paramagnetic molecule treated magnetic tunnel junction tended to settle in the suppressed state at room temperature.

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Why is it important?

This paper shows the effect of molecular spin channels between two ferromagnetic electrodes. Molecules impacted the ferromagnetic electrode over a large area and yielded dramatic current suppression observation at room temperature. Molecules forced Magnetic Tunnel Junction(MTJ) testbed to acquire as low as seven orders of magnitude smaller current as compared to the one before introducing molecules on MTJ.

Perspectives

The molecular spintronics field mainly assumes that a molecular device channel is a bridge of spin transport. However, we have seen that molecules transform the magnetic properties of the magnetic tunnel junctions and produced equally drastic changes in transport properties at room temperature. These observations are mainly due to the fact that MTJ based molecular spintronics device approach allows molecules to demonstrate their full potential by keeping role of interfering defects to the minimum or negligible. Prior studies using ferromagnetic break junction showed some dramatic observations. However, using MTJ as a testbed for molecular spintronics provide unprecedented advantages not possible otherwise.

Director of Center for Nanotechnology Research and Education Pawan Tyagi
University of the District of Columbia

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This page is a summary of: Magnetic tunnel junction based molecular spintronics devices exhibiting current suppression at room temperature, Organic Electronics, January 2019, Elsevier,
DOI: 10.1016/j.orgel.2018.10.030.
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