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

Gd3+ complexes have been shown to undergo unusual slow magnetic relaxation processes similar to those of single-molecule magnets (SMMs), even though Gd3+ does not exhibit strong magnetic anisotropy. To reveal the origin of the slow magnetic relaxation of Gd3+ complexes, we have investigated the magnetic properties and heat capacities of two Gd3+ -phthalocyaninato triple-decker complexes, one of which has intramolecular Gd3+ -Gd3+ interactions and the other does not. It was found that the Gd3+ -Gd3+ interactions accelerate the magnetic relaxation processes. In addition, magnetically diluted samples, prepared by doping a small amount of the Gd3+ complexes into a large amount of diamagnetic Y3+ 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.