d-Orbital Orientation-Governed Room-Temperature Magnetism in Charge Transfer Cocrystals

The design of molecular magnets with programmable spin states at room temperature is challenging for quantum materials. Although organic charge transfer (CT) cocrystals offer a promising framework for tuning spin states through electronic coupling, the deliberate design of donor (D)-acceptor (A) pairs and based on orbital-regulation strategy to mediate effective magnetic interactions has remained unexplored. Here we prove that CT cocrystals provide a platform where metal orbital characteristics govern magnetic strength, while the ordered CT lattice mediates long-range exchange interactions to support collective magnetic ordering. We obtained C60-H2TPP, C60-CuTPP, C60-CoTPP with successively increasing ferromagnetism at 300 K. Through orbital-regulation strategy, the substitution of metal ion Cu2+ with Co2+ precisely reorients the unpaired electron orbital from an alignment parallel to the donor molecule plane to one that points directly toward the C60 molecule. This spatial orientation leads to a significant enhancement in saturation magnetization, revealing that the orbital orientation of the D and A molecules can systematically govern the ferromagnetic ground state in cocrystals. Our results support orbital-regulation strategy as an effective design principle for room-temperature molecular magnets, with implications for spintronic applications based on organic quantum materials.