Local spin dynamics in doped cobalt(II)-radical magnetic chains studied by H-1 NMR

We investigated the spin dynamics of Zn(II)-doped ‘‘single-chain magnet” (SCM) Co(hfac)2NITPhOMe (in
short CoPhOMe) by means of 1H NMR measurements. CoPhOMe was the first magnetic chain that showed
a slowly relaxing magnetization (commonly called spins’ or magnetization ‘‘slowing down” mechanism),
which follows the predictions of the Glauber model: the electronic spin freezing sets in before any transition
to long-range magnetic order. The nuclear spin–lattice relaxation rate at different applied magnetic fields, displayed a high temperature peak and a low-temperature shoulder that become lower and shifts toward higher temperatures
with increasing the field. This behaviour is qualitatively in agreement with the recent AC susceptibility
data that revealed the Glauber dynamics and finite-size effects, like the collective reversal of the
spins of each chain segment.