Anomalous magnetic properties of the complex (ET)(2)C-60

Investigations of the temperature dependences of the magnetic permeability and dielectric permittivity in the temperature range 4.2 K less than or equ al to T less than or equal to 300 K and the field dependence of the magneti zation M(B) in fields B less than or equal to 50 T show that the magnetic p roperties of the complex (ET)(2)C-60 cannot be described on the basis of th e standard model, which assumes that the paramagnetic oxygen impurity makes the dominant contribution. It is found that the magnetism in (ET)(2)C-60 i s due to the diamagnetic properties of the C-60 and ET molecules and to spe cific paramagnetic centers of the type C-60(-), which possess an anomalousl y low g factor \g\approximate to 0.14. An experimentum crucis is proposed f or checking the oxygen paramagnetic center model for pure C-60 films. (C) 1 999 American Institute of Physics. [S0021-3640(99)01210-4].