First-Principles Calculations of Magnetic Moment Modulation of 3d Transition Metal Atoms Encapsulated in C₆₀/C₇₀ Cages on Si(100) Surfaces: Implications for Spintronic Devices

Manipulations of single atoms or molecules at the nanoscale have significant potential for applications in microelectronic devices. Magnetic materials are widely used in the fields of information storage and spintronics. Here, we study the controllability of the moment of 3d transition metal (TM) atoms adsorbed on the Si(100) surface using first-principles calculations. The TM atoms lose their magnetic moment due to hybridization with the substrate. If the TM atoms are encapsulated in a C60 or C70 cage, the magnetic moments can be preserved due to the shielding effect. The cages can isolate the atoms from direct hybridization with the substrate. Interestingly, we found that C70 has a stronger protecting effect, even with an impurity level located above the Fermi level. Based on the Anderson impurity model, this exotic phenomenon can be attributed to the presence of linear dispersion around the Fermi level. This work provides an experimental strategy for modulating the magnetic moments in nanoscale systems, which is also beneficial for the design of silicon-based spintronic devices.