Macroscopic magnetic measurements on the nonferromagnetic modification of TDAE-C60

We present macroscopic magnetic measurements on single crystals of the nonferromagnetic ${\alpha }^{\prime }$ modification of TDAE-${\mathrm{C}}_{60}$ in a wide temperature (2 K $<T<\mathrm{}100\mathrm{}$ K) and field $(0<H<\mathrm{}50\mathrm{}$ kOe) range. Results show that the low-temperature magnetic properties of ${\alpha }^{\prime }-\mathrm{TDAE}-{\mathrm{C}}_{60}$ can be described in terms of simple paramagnetic model of noninteracting spins with the effective number of spins corresponding to one Bohr magneton ${\mu }_B$ per formula unit. The effective number of spins gradually increases from one to two ${\mu }_B$ per formula unit as the temperature rises towards 100 K. We propose a model of two independent magnetic subsystems with different spin interactions which could account for the observed magnetic behavior of ${\alpha }^{\prime }-\mathrm{TDAE}-{\mathrm{C}}_{60}.$