Novel spin dynamics in ferrimagnetic molecular chains from 1H NMR and MuSR spin-lattice relaxation measurements

The spin dynamics in the helical chain Co(hfac)(2)NITPhOMe has been investigated by H-1 NMR and muSR relaxation. In the temperature range 15 < T < 60 K, the results are consistent with the relaxation of the homogeneous magnetization. For Tless than or equal to 15 K, NMR and muSR evidence a second spin relaxation mechanism, undetected by the magnetization measurements. From the analysis of these data, insights on this novel relaxation process are derived.