Ferromagnetism in C60 polymers: pure carbon or contamination with metallic impurities?
A review of ferromagnetism in C60 polymeric materials synthesized by high pressure high temperature (HPHT) treatment is presented. Analysis of published data proves that the reported ferromagnetism cannot be assigned to polymeric structure in either perfect or defect states. Most recent experimental studies have not confirmed previously reported levels of magnetization in polymeric samples while it appears that ferromagnetism of "magnetic carbon" is preserved above the depolymerization point of any C60 polymer. Identical ferromagnetic properties in some samples of fullerene polymer and graphite like hard carbon phase also show that the effect is most likely not connected to fullerenes at all. Most of the data published previously as an evidence of ferromagnetism in C60 polymers synthesized at HPHT conditions can be explained by contamination with magnetic impurities. Formation of iron carbide (Fe3C) due to reaction of metallic iron with fullerene molecules allows to explain observed Curie temperature of approximately 500 K and levels of magnetization reported for "magnetic carbon".
Talyzin
A V
AV
Department of Physics, Umeå University, SE-901 87 Umeå, Sweden.
Dzwilewski
A
A
D002244:Carbon / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D004583:Electrons; D037741:Fullerenes / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry; D008280:Magnetics; D008670:Metals / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D011108:Polymers / Q000737:chemistry*; D013696:Temperature
D037741:Fullerenes; D058085:Iron Compounds; D008670:Metals; D011108:Polymers; D002244:Carbon; D006859:Hydrogen; C069837:fullerene C60