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The 1H and 13C NMR as well as the X-band and high-field EPR spectra of TDAE-C70 are compared with those of TDAE-C60. The observation of a weak temperature dependent high-field EPR line below 50 K may be connected with the occurrence of a ferromagnetic modification of TDAE-C70 in addition to the well known paramagnetic one. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Ti NMR and the field swept pulsed EPR spectra of bulk powder anatase TiO2 and TiO2 based nanotubes have been found to be radically different. The same is true for the magnetic properties measured by SQUID. Whereas no EPR line could be detected for the TiO2 powder, a rather strong temperature dependent line has been seen for TiO2 based nanotubes. The magnetization versus magnetic field curve of uncompressed TiO2 based nanotubes at 5 K shows the presence of a huge jump-wise increase in the magnetization at about 4 T, which disappears at 1 T as well as in the compressed sample. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The frequency swept wide line [SUP13]C NMR spectra of well annealed [SUP13]C enriched TDAE-C[SUB60] demonstrate below 10 K a sudden increase in the inhomogeneous linewidth indicating a Jahn-Teller distortion. The distortion is dynamic above 10 K and becomes static on the [SUP13]C NMR time scale below this temperature. From the [SUP13]C NMR lineshape a belt-like unpaired electron spin density distribution on the C[SUB60-] ion can be extracted. [ABSTRACT FROM AUTHOR]

The temperature dependence of the [sup13]C NMR spectra of a 40 percent [sup13]C enriched well annealed TDAE-C[sub60] sample has been measured at a Larmor frequency v[subL] = 95.57 MHz in a field of 9 T between 300 K and 7 K. Three transitions are found: the motional transition around 150 K, the ferromagnetic transition which occurs in a field of 9 T at T[subc] = 24 K, and a transition to an inhomogeneous ferromagnetic phase around 9 K. The [sup13]C spectra are dominated by the Fermi contact interaction between the unpaired electron and the [sup13]C nuclei as well as by the electronnuclear dipolar interactions. The temperature dependence of the observed lineshapes can be understood by a superposition of uniaxial rotations of the C[sub60] ions around their 3-fold axes plus a flipping of the axes of rotation. The flipping starts to freeze out below the motional transition at 150 K whereas uniaxial rotational jumps seem to persist down to the lowest temperature studied. The results are compatible with the C[sub60] orientational disorder proposed by Narymbetov et al. maximizing the ferromagnetic exchange interactions. [ABSTRACT FROM AUTHOR]