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

Yoji Horii; Keiichi Katoh; Yuji Miyazaki; Marko Damjanović; Tetsu Sato; Liviu Ungur; Liviu F Chibotaru; Brian K Breedlove; Motohiro Nakano; Wolfgang Wernsdorfer; Masahiro Yamashita

doi:10.1002/chem.201905796

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

Chemistry. 2020 Jun 26;26(36):8076-8082. doi: 10.1002/chem.201905796. Epub 2020 Jun 5.

Authors

Affiliations

¹ Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
² Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.
³ Research Center for Thermal and Entropic Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan.
⁴ Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
⁵ Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
⁶ Theory of Nanomaterials Group, Katholieke Universiteit Leuven, 3001, Leuven, Belgium.
⁷ School of Materials Science and Engineering, Nankai University, Tianjin, 300350, China.

PMID: 32057140
DOI: 10.1002/chem.201905796

Abstract

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.

Keywords: gadolinium; magnetic properties; phonon-bottleneck effect; porphyrinoids; spin-lattice relaxation.

Abstract

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