Carbon cage confinement enhances magnetic anisotropy of single-molecule magnets Dy2O@C3v-C82 and Dy2S@C3v-C82.

This study investigates the structural and magnetic properties of endohedral metallofullerenes Dy2O@C3v-C82 and Dy2S@C3v-C82 through DFT and CASSCF methods. The results show that Dy2O@C3v-C82 exhibits a longer quantum tunneling of magnetization relaxation time and a higher effective energy barrier (Ueff) compared to Dy2S@C3v-C82. The rigid carbon cage framework enhances the local crystal field with strong axial anisotropy, effectively suppressing contributions from transverse fields and thereby inhibiting quantum tunneling of magnetization. Dynamic structure analysis shows that the encapsulated metal cluster is the dominant contributor to variations in the axial crystal field, while the carbon cage also plays a significant role. These findings underscore the essential role of the carbon cage in enhancing magnetic anisotropy and improving the magnetic performance of Dy2O@C3v-C82 and Dy2S@C3v-C82.