Gold-Coated Transition-Metal Anion [Mn<sub>13</sub>@Au<sub>20</sub>]<sup>-</sup> with Ultrahigh Magnetic Moment

Structures and magnetic properties of gold-coated transition-metal clusters [Mn<sub>13</sub>@Au<sub>20</sub>]<sup>-</sup> and [Co<sub>13</sub>@Au<sub>20</sub>]<sup>-</sup> are studied within the framework of gradient-corrected density functional theory. The gold coating can result in either an enhanced or an attenuated effect on the magnetism of the core clusters. For [Mn<sub>13</sub>@Au<sub>20</sub>]<sup>-</sup>, the total magnetic moment is greatly enhanced to as high as 44 μ<sub>B</sub>, more than 20-fold higher than that of the bare Mn<sub>13</sub><sup>-</sup> cluster. For [Co<sub>13</sub>@Au<sub>20</sub>]<sup>-</sup>, however, the gold coating gives rise to an attenuation effect which leads to a reduction of the magnetic moment to 20μ<sub>B</sub> from 30μ<sub>B</sub> of the bare Co<sub>13</sub><sup>-</sup> cluster.