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μ SR studies of organic and molecular magnets

Muon-spin rotation and relaxation (muSR) experiments have been performed on a variety of novel organic and molecular magnetic systems. In these experiments, implanted muons are used to study the magnitude, distribution and dynamics of the local field at the muon site. Calculations of the spatial dependence of the dipole-field inside the unit cell are used to interpret the data and determine the muon site in certain cases. We describe and review muon experiments on nitronyl nitroxide organic ferromagnets and antiferromagnets. We discuss a muon study of the spin crossover phenomenon which has been studied in Fe(PM-PEA)(2)(NCS) (2), and which shows Gaussian and root- exponential muon relaxation in the high-spin and low-spin phases, respectively. The effects of high temperature annealing on TDAE-C-60 have also been studied with muSR. Experiments on a disc-shaped molecular complex containing Fe-19 (with spin 31/2) reveal the effects of fluctuations of magnetization and allow an estimate of the fluctuation rate. These experiments demonstrate the wide range of problems which can be tackled using the muSR technique.

muon-spin rotation ; organic magnet ; nanodisc ; quantum tunneling ; molecular magnet

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