Evidence for high-temperature ferromagnetism in photolyzed C-60
2004 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 3Article in journal (Refereed) Published
C-60 transforms to a polymeric phase where the C-60 molecules are bonded to form a chain structure when it is subjected to ultraviolet radiation at ambient temperature in the absence of oxygen. The electron paramagnetic resonance spectrum of C-60 photolyzed in the presence of a low pressure of oxygen or in air shows a very broad, asymmetric derivative signal at room temperature and at a magnetic field position well removed from g=2.000. With decreasing temperature, the broad line shifts to lower magnetic fields and increases further in linewidth, as expected for a ferromagnetic resonance signal. A low-field nonresonant derivative signal is also observed, consistent with the existence of ferromagnetism. Ferromagnetism up to room temperature in photolyzed C-60 is confirmed unequivocally by superconducting quantum interference device measurements of the dc magnetization as a function of magnetic field. A possible model for the origin of ferromagnetism based on these results and Raman data on photolyzed samples is also proposed.
Place, publisher, year, edition, pages
2004. Vol. 69, no 3
photoinduced polymerization, oxidation, absorption, films, c60
IdentifiersURN: urn:nbn:se:kth:diva-23164DOI: 10.1103/PhysRevB.69.033403ISI: 000188883800016ScopusID: 2-s2.0-1442263837OAI: oai:DiVA.org:kth-23164DiVA: diva2:341862
QC 20100525 QC 201110312010-08-102010-08-102011-10-31Bibliographically approved