Relaxation dynamics in a Fe7 nanomagnet

We investigate the phonon-induced relaxation dynamics in the Fe 7 magnetic molecule, which is made of two Fe 3 + triangles bridged together by a central Fe 3 + ion. The competition between different antiferromagnetic exchange interactions leads to a low-spin ground state multiplet with a complex pattern of low-lying excited levels. We theoretically investigate the decay of the time correlation function of molecular observables, such as the cluster magnetization, due to the spin-phonon interaction. We find that more than one time contributes to the decay of the molecular magnetization. The relaxation dynamics is probed by measurements of the nuclear spin-lattice relaxation rate 1 /T 1 . The interpretation of these measurements allows the determination of the magnetoelastic coupling strength and to set the scale factor of the relaxation dynamics time scales. In our theoretical interpretation of 1 /T 1 data we also take into account the wipeout effect at low temperature