Two-dimensional crystals with ferromagnetic ordering would lead to unprecedented possibilities for magnetic, magneto-optic, and magnetoelectric applications. However, long-range ferromagnetic ordering in two-dimensional van der Waals materials is strongly diminished by thermal fluctuation, while three-dimensional systems show the stiffness of magnetic ordering temperature to magnetic fields. Here, we report the discovery of intrinsic ferromagnetic ordering temperature of 60 K in an iron/tetracyanoquinodimethane layer via superconducting precursor. In such a molecular ferromagnet, an unprecedented control of ferromagnetic fluctuation temperature by ∼200% improvement is realized through magnetic fields. We demonstrate magnetodielectric coupling with a concomitant transition in magnetic ordering. A small magnetic field of 0.01 T enables an effective route to realize a sizable transition shift in magnetodielectric states. Stimulated by photoirradiation, it manifests a hidden metallic conducting state, declaring a metallic ferromagnet. The molecular ferromagnet and photoirradiation-induced hidden metallic phase present a “holy grail” in the field of molecular conducting magnets.

具有铁磁有序的二维晶体将为磁性，磁光和磁电应用带来前所未有的可能性。但是，二维范德华材料的远距离铁磁有序性会因热波动而大大降低，而三维系统则显示出磁场对磁场的有序性。在这里，我们报告了通过超导前体在铁/四氰基对二甲烷层中发现60 K的固有铁磁有序温度的过程。在这种分子铁磁体中，通过磁场实现了对铁磁波动温度前所未有的控制，可将磁化波动温度提高约200％。我们展示了磁电耦合，并伴随着磁序跃迁。0的小磁场。01 T实现了一条有效的途径，可在磁电状态下实现相当大的转变。受光辐照刺激，它表现出隐藏的金属导电状态，表明是金属铁磁体。分子铁磁体和光辐射诱导的隐藏金属相是分子导电磁体领域的“圣杯”。