Quantum fluctuations of the magnetization in high spin molecules - a mu SRstudy

Using zero field (ZF) and longitudinal field (LF) mu SR we study the magnet ic properties of high spin molecules (HSM) with spin S = 15/2 and 27/2. The LF-mu SR at very low temperatures suggests that in both our samples dynami cal field fluctuations are responsible for the muon relaxation. The relaxat ion rate lambda increases as the temperature decreases and then saturates b elow T < T-c indicating that the dynamics is of quantum nature. The fluctua tion rate at T --> 0 of the different samples is compared. (C) 2000 Elsevie r Science B.V. All rights reserved.