Interfacial Engineering Enabled the Tunability of Organic Spin Polarization

Organic charge-transfer ferromagnets have been studied for many years, and numerous breakthroughs have been made pertaining to them. However, the mechanism underlying the phenomenon is still unclear. Herein, we designed organic charge-transfer ferromagnets using different small molecule acceptors to investigate the key factors determining ferromagnetic performance. We found that the electron–phonon (e–p) coupling of the acceptors affects the interfacial interaction, which in turn changes the strength of ferromagnetism. Under an external magnetic field, the e–p coupling in the acceptors intensifies, yielding a weak interfacial spin–dipole interaction. The charge-transfer ferromagnets exhibited magnetic anisotropy due to the difference in the spatial structure symmetry of acceptors. Overall, this study deepens the understanding of interfacial interactions in organic charge-transfer ferromagnets, providing a new perspective for designing organic ferromagnets.