Gadolinium as an accelerator for reaching thermal equilibrium and its influence on the ground state of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Dy</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>GdN</mml:mi><mml:mo>@</mml:mo><mml:msub><mml:mi mathvariant="normal">C</mml:mi><mml:mn>80</mml:mn></mml:msub></mml:mrow></mml:math> single-molecule magnets

Endohedral fullerenes are perfect nanolaboratories for the study of magnetism. The substitution a diamagnetic scandium atom in Dy2ScN@C80 with gadolinium decreases stability given magnetization and demonstrates Gd to act as single catalyst that accelerates reaching thermal equilibrium. X-ray magnetic circular dichroism at M4,5 edges Dy shows moment follows sum external dipolar field two ions compared lower exchange barrier is found between ferromagnetic antiferromagnetic configuration. Arrhenius equilibration obtained from superconducting quantum interference device magnetometry more than one order magnitude larger, though much smaller prefactor imposes faster Dy2GdN@C80. This sheds light on importance angular momentum balance relaxation.