Plasmon Excitations in Spin-Polarized Iron Atomic Chains: A Time-Dependent Density Functional Theory Study

Abstract

Abstract By using the time-dependent density functional theory calculations, we study the plasmon excitations in Fe atomic chains with different numbers of atom and different Fe-Fe separations, which are now possible to fabricate experimentally. Because of the Fe valence 3d orbitals and the spin polarization, the excitations along the chain (longitudinal (L) mode) and perpendicular to the chain (transverse (T) modes) are found to be largely different from those in noble metal and alkali metal atomic chains. First, the strength of dipole response becomes weaker due to the more localized Fe 3d states; Second, the L mode is mixed with some multipole contribution; Third, the end mode of the T modes is absent.