Study of the influence of nuclear spin and dilution over the slow relaxation in a 3d4f heterobimetallic single-molecule magnet

The effects of isotopic enrichment and magnetic dilution have been investigated in a heterobimetallic complex of formula [Zn 2 L 2 A DyCl 3 ]·2H 2 O ( A DyZn 2 ) (A = 162 and 163) presenting slow relaxation of the magnetization. Isotopic substitution for 162 Dy (I = 0) and 163 Dy (I = 5/2) leads to a shift in the relaxation times depending on the suppression or enhancement of the hyperfine interactions. The release of the dipolar interactions through magnetic dilution in a Y(iii)-based matrix enhances the slow relaxation of the magnetization and the visibility of the nuclear spin effect. A comparison of the hysteresis loop at 0.5 K for bulk and diluted analogues of pure isotopically enriched complexes suggested a role of the nuclear spin in the interaction between the active system and the matrix.