Continuous Room-Temperature Spin-Injection Modulation Achieved by Spin-Filtering Competition in Molecular Spin Valves

Abundant spin-related phenomena that originate from interfaces between ferromagnetic electrodes and molecular semiconductors have greatly enriched research in spintronics, and they are considered promising for realizing novel spintronic functionalities in the future. However, despite great effort, the interfacial effect cannot be precisely controlled to achieve steady and predictable functions, especially at room temperature, and this has gradually become a significant bottleneck in the development of molecular spintronics. In this study, an innovative spin-filtering-competition mechanism is proposed to continuously modulate the interfacial effect in molecular spin valves at room temperature. To form this novel mechanism, the original spin-filtering effect from pure cobalt competes with the newly generated one, which is induced by the bonding effect between cobalt and lithium fluoride. Subsequently, by precisely controlling competition through lithium fluoride coverage on the cobalt surface, continuous modulation of the spin-injection process can be successfully achieved at room temperature. Spin polarization of the injected current and magnetoresistance effect can be actively controlled or their sign can be completely reversed through this novel mechanism. This study provides an innovative approach and theory for precisely controlling spin-related interfacial effects, which may further promote the scientific and technological development of spintronics.