Abstract
The spin-Peierls state in the organic compound MEM(TCNQ)2 is studied by magnetisation measurements in magnetic fields up to 50 T. The possible universality of the magnetic field vs. temperature magnetic phase diagram of spin-Peierls systems is investigated by comparing the results on MEM(TCNQ)2 with the corresponding data for the inorganic spin-Peierls compound CuGeO3. Although the transition line between the uniform and the dimerised phase follows the same dependence for both compounds, strong discrepancies are found for the phase boundary between the dimerised and the high-field magnetic phase.