Diverse Superatomic Magnetic and Spin Properties of Au₁₄₄(SC₈H₉)₆₀ Clusters

Au₁₄₄(SC₈H₉)₆₀, a colloidal cluster with a 1.7 nm inorganic diameter, exhibits both metallic and molecular-like behavior, along with a distribution of unfilled superatom states. Its 1.7-2.5 eV electronic transitions were probed with variable-temperature, variable-field magnetic circular dichroism (VTV <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover><mml:mrow><mml:mi>H</mml:mi></mml:mrow> <mml:mrow><mml:mo>⇀</mml:mo></mml:mrow> </mml:mover> </mml:math> -MCD), revealing two energy regions with distinct responses. Below 2.0 eV, MCD transitions exhibited diverse VTV <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover><mml:mrow><mml:mi>H</mml:mi></mml:mrow> <mml:mrow><mml:mo>⇀</mml:mo></mml:mrow> </mml:mover> </mml:math> responses, including both paramagnetic and diamagnetic behavior, implicating multiple nondegenerate initial states originating within the open-shell superatom S, D, and H HOMO manifold. Above 2.0 eV, uniform field-dependent responses suggested spin-vibronic coupling due to metal-ligand mixing. The Au₁₄₄(SC₈H₉)₆₀ magneto-optical response is surprisingly complex given the system's high electronic-state density; discrete structural domains of the cluster, including the superatomic metal core, likely contribute to this diversity. These results show the potential to investigate and tailor the magneto-optical and spin properties of these clusters through structurally precise synthesis and also identify superatomic colloids as candidates for advancing spin-based technologies.