Effects of spin polarization on the propagation of surface waves on a quantum plasma half-space

Abstract

The study explores the wave propagation characteristics of surface plasma waves in a semi-bounded plasma, incorporating the influence of spin polarization arising from spin mismatch. The formulated plasma model integrates the density correlation effect via Bohm's potential force, Fermi pressure employing Fermi-Dirac statistics, and the exchange potential. These factors are considered in spin-polarized form and interconnected through the spin polarization index κ. We derive a dispersion relation for surface plasma waves, delineating the propagation features of the configured wave mode. Our findings indicate that an increase in spin polarization among electron populations results in a decrease in the phase velocity of surface plasma waves compared to the usual electron-ion quantum plasma. Moreover, an increase in the exchange potential contributes to a decrease in the phase speed. However, the ratio of plasmon to Fermi energy leads to an increase in the phase velocity of surface plasma waves in a spin-polarized quantum plasma. We provide a comparative analysis of our work with an earlier model based on the gold–air interface, revealing that our model facilitates the propagation of surface plasma waves with higher frequencies across the wave vector. This study highlights the significance of quantum effects for electrostatic surface plasma waves in dense metallic plasmas at room temperature, with implications for signal transmission in metallic waveguides observed in a recent study [Guo et al., “Excitation of graphene magneto-plasmons in terahertz range and giant Kerr rotation,” J. Appl. Phys. 125(1), 013102 (2019)] and some of the references therein.