Amination of the Gd@C₈₂ endohedral fullerene: tunable substitution effect on quantum coherence behaviors

The core-shell structure of endohedral fullerene-based anisotropic magnetic molecules of high spin with long coherence time could help scale up quantum systems. In this research, by amination of Gd@C₈₂ with morpholine, three derivatives are functionalized with 5, 7 and 9 morpholine groups providing an interesting model to investigate the relationship between the quantum coherence and the spin environment. The original radical located on the carbon cage is successfully quenched, affording a quantum phase memory times (T _M) over 5 μs at 5 K. By increasing the number of substitution groups, spin-lattice relaxation times (T ₁) also show significant enhancement due to the interaction variation between the molecules and the environments. We found that the T _M of the three molecules show no obvious difference below 10 K, while they are limited by T ₁ at higher temperatures. In this work, the variable functional groups are able to tune both T ₁ and T _M, offering the possibility for application of high-spin magnetic molecules in the field of quantum information processing.