Carbon is conventionally not associated with magnetism, causing much of the discussion of its perspectives in nanotechnology to be centred on its electron-transport properties. Among the few existing examples of magnetic carbon production, none has found a direct route into scalable micro- and nanofabrication. Here we introduce a magnetic form of carbon whose precursor polymers can be lithographically patterned into micro- and nano-structures prior to pyrolysis. This unreactive and thermally robust material features a strong, room-temperature magnetism owing to a large number of unpaired electron spins with restricted mobility, which is achieved by controlling the progression of bond dissociation and formation during pyrolysis. The micro-manufacture of pyrolytic magnetic carbon, having (3.5±0.7)×1015 spins/mg, can immediately benefit a number of spintronic and magnetic-microelectromechanical system applications, and the fabrication of composite magnetic materials. The material could also complement the magnetic resonance spectroscopy and imaging techniques. Additionally, this contribution sheds light on the controversial theories concerning the existence and mechanism of magnetic phenomena in carbon.

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