Magnetic coupling engineering-induced excellent spin transport in covalently linked nanographene dimers

Abstract

A generally accepted viewpoint is that molecules with a spin S = 1/2 did not show any magnetic coupling when assembled into molecular dimers. However, a recent experiment successfully synthesizes covalently linked five-membered ring decorated nanographene dimers that are antiferromagnetically coupled with each other [Phys. Rev. Lett. 124 (2020) 147206]. Motivated by this work, we further study the effect of magnetic coupling engineering on spin transport properties in covalently linked nanographene dimers-based molecular devices. Our results show that excellent spin transport properties are strongly dependent on the magnetic coupling strength of the covalently linked five-membered ring decorated nanographenes. A variety of interesting spin transport properties are found, including “inverse Schottky” characteristic, high spin polarization, reverse of spin polarization, and large magnetoresistance. These results indicate that the covalently linked five-membered ring decorated nanographene dimers can be designed as over-current protection devices, and information storage and logic devices by engineering of magnetic coupling. Our works confirm an efficient way for building high-performance carbon-based molecular spintronic devices.