ABSTRACT Co(II)‐based coordination polymer is reported as a new benchmark single‐chain magnet (SCM), exhibiting an energy barrier ( U eff ) of 560 K and a blocking temperature ( T B ) of 21.5 K‒both the highest values observed for SCM systems. The magnetic behavior originates from the synergistic balance between strong axial anisotropy ( D Co = –83 cm −1 ) and moderate ferromagnetic exchange ( J Co‐Co = +17.7 K), promoting long‐range spin correlation over thousands of magnetic ions. Detailed analysis of the correlation length and domain‐wall energy reveals a wide SCM regime and a 1D‐to‐3D magnetic crossover at low temperature. Unlike previously reported radical‐bridged SCMs, this work demonstrates a clean, intrinsic design strategy for realizing extreme single‐chain magnetism, offering new principles for developing robust molecular spin materials.
Cui et al. (2025) studied this question.