Interplay between the d - and π -electron systems in magnetic torque of the layered organic conductor κ -(BETS) 2Mn[N(CN)2]3

In the organic charge transfer salt k-(BETS)2Mn[N(CN)2]3 the metallic conductivity is provided by itinerant pi-electrons in the layers of BETS molecules, whereas magnetization is largely dominated by the localized d-electrons of the Mn2+ ions in the insulating anionic layers. We study magnetic properties of the compound in its low-temperature, Mott-insulating state by means of magnetic torque technique. The complex behavior of the torque can be qualitatively explained by the coexistence of two weakly interacting magnetic subsystems associated with paramagnetic d-electron spins and antiferromagnetically ordered pi-electron spins, respectively. Based on the experimental data, we determine the principal axes of magnetization of the Mn2+ sublattice and propose a qualitative model for the pi-electron spin arrangement, implying an important role of the Dzyaloshinskii-Moriya interaction.