We describe preparation and magnetic properties of an organic π-conjugated polymer with very large magnetic moment and magnetic order at low temperatures. The polymer is designed with a large density of cross-links and alternating connectivity of radical modules with unequal spin quantum numbers (S), macrocyclic S = Z and, cross-linking S = 1/2 modules, which permits large net S values for either ferromagnetic or antiferromagnetic exchange couplings between the modules. In the highly cross-linked polymer, an effective magnetic moment corresponding to an average S of about 5000 and slow reorientation of the magnetization by a small magnetic field (less than or equal to 1 oersted) below a temperature of about 10 kelvin are found. Qualitatively, this magnetic behavior is comparable to that of insulating spin glasses and blocked superparamagnets.
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