Valley-polarized edge plasmons in graphene p–n junctions with pseudomagnetic fields

Abstract

Owing to the inherent characteristics of collective excitations in graphene, electrical control of edge plasmons is highly desirable for nanoplasmonic applications. This study investigates valley-polarized edge pseudomagnetoplasmons in a graphene p–n junction subjected to a strain-induced pseudomagnetic field. A four-component hydrodynamic model is employed and solved via the Wiener–Hopf method, revealing the coexistence of three plasmon modes, including counterpropagating acoustic edge modes, gapless topological edge states, and zero modes. The valley polarization, as determined from the numerically exact solution, is stronger than that predicted by the approximate models. Notably, the confinement of edge plasmons at the graphene p–n junction significantly exceeds that at the graphene/vacuum interface, possibly because of the electron–hole attraction. Furthermore, gate-controlled subwavelength confinement is successfully achieved by applying an appropriate gate voltage, thereby highlighting a unique and promising attribute of edge pseudomagnetoplasmons in graphene p–n junctions.