Coexistence of Spin-Lattice Relaxation and Phonon-Bottleneck Processes in Gd -Phthlocyaninato Triple-Decker Complexes under Highly Diluted Conditions.

Gd complexes have been shown to undergo unusual slow magnetic relaxation processes similar to those of single-molecule magnets (SMMs), even though Gd does not exhibit strong magnetic anisotropy. To reveal the origin of the slow magnetic relaxation of Gd complexes, we have investigated the magnetic properties and heat capacities of two Gd -phthalocyaninato triple-decker complexes, one of which has intramolecular Gd -Gd interactions and the other does not. It was found that the Gd -Gd interactions accelerate the magnetic relaxation processes. In addition, magnetically diluted samples, prepared by doping a small amount of the Gd complexes into a large amount of diamagnetic Y complexes, underwent dual magnetic relaxation processes. A detailed dynamic magnetic analysis revealed that the coexistence of spin-lattice relaxation and phonon-bottleneck processes is the origin of the dual magnetic relaxation processes.