The quest for magnetic polymers—caveat emptor

Abstract

Numerous reports claiming ferromagnetic behavior in organic polymers exist; however, the reported materials have been plagued by ill‐defined compositions, low yields on a magnetic basis, and poor reproducibility. Such low values of saturation magnetization (i.e., ≪ 5600 emuG/mol spin) cause serious concern as to whether the magnetic behavior arises from extrinsic sources and thus obligate the researcher to provide a persuasive case that when a material has a low saturation magnetization, suggesting thrtt the magnetic fraction is only a small portion of the bulk, that the magnetic behavior is in fact intrinsic and not of extrinsic origin. In several cases, when reinvestigated, the magnetic behavior of reported polymeric magnetic materials has been attributed to extrinsic sources. In the cases where extrinsic sources have not been identified, verification of the magnetic behavior has not been reported by independent laboratories. Thus, to date there have not been any reports of a bulk polymer that have stood the test of confirmation for ferromagnetic or even ferrimagnetic behaviour. Hence, caveat physics—scientist beware.