Acceptor-Donor Molecular Heterojunction Control of π-Orbital-Induced Magnetic Properties of a 3d Ferromagnet.

Ozdemir, Servet; Rogers, Matthew; Aslam, Zabeada; Ali, Mannan; Teobaldi, Gilberto; Moorsom, Timothy; Hickey, B J; Cespedes, Oscar · Nano Lett · 2025

basic_science · Level V

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Abstract

Metal-organic molecule interfaces have given rise to a wide range of magnetic phenomena. These effects arise due to spin-polarized charge transfer and enhanced exchange interaction at metallo-molecular hybridization sites, where tunability via electric fields beyond ferroelectric interfaces remains to be demonstrated. Here, we explore manipulating the magnetism of cobalt with the intrinsic electric field generated at C<sub>60</sub>/phthalocyanine heterojunctions, a combination commonly used in organic photovoltaics. The results give evidence for a C<sub>60</sub> layer thickness-dependent control of hybridization effects on cobalt. We find that the heterojunctions may attenuate the hybridization effects, with changes in coercivity and magnetization due to the built-in electric field. An emergent exchange bias is attributed to an enhanced Rashba interaction for thicker C<sub>60</sub> layers. Our study clarifies some of the questions in the field of molecular "spinterface" physics and demonstrates that internal electric field generation is a promising method for manipulation of metallo-molecular interfaces up to room temperature.