Effect of dynamic ions on band structure of plasmon excitations

Abstract

In this paper, we develop a new method to study the plasmon energy band structure in multispecies plasmas. Using this method, we investigate a plasmon dispersion band structure of various quasineutral plasma systems with arbitrary degree of electron degeneracy. The linearized Schrödinger–Poisson model is used to derive an appropriate coupled pseudoforce system from which the energy dispersion structure is calculated. It is shown that the introduction of ion dynamics, as opposed to static ion assumption in the jellium model with a wide plasmon bandgap, can significantly modify the plasmon dispersion character leading to a new low-level energy band caused by the electron–ion interactions. The investigation on the effect of ion charge-state and chemical potential of electrons on the plasmonic band structure indicates some interesting features and reveals the fundamental role played by ions in the phonon assisted plasmon excitations in different kinds of plasma systems. Moreover, our study confirms that ion charge screening has a significant impact on plasmon excitations in multispecies plasmas. The plasmon band structure in pair-ion or electron–positron plasmas indicates the unique role of positive charges on collective excitations. Current research helps us to better understand the underlying mechanisms of collective interactions in charged environment and the important role played by heavy charged particles on elementary plasmon excitations, which have important applications in plasmonic devices. The method developed in this research may also be extended to study magnetized quantum plasmas as well as to investigate surface plasmon–polariton interactions in nanometallic structures.