Spin freezing in geometrically frustrated magnetic molecule Fe30 revealed by NMR

Static and dynamical properties of Fe3+ (3d5; S = 5/2) spins in geometrically frustrated magnetic molecule Fe30 have been investigated by nuclear magnetic resonance (NMR) in the temperature range T = 0.1–300 K From a measurement of nuclear spin-lattice relaxation rates as a function of temperature, the fluctuation frequency of Fe3+ spins is found to decrease with decreasing temperature, indicating spin freezing at low temperatures.