Tunable surface plasmon-polaritons in a gyroelectric slab sandwiched between two graphene layers

•External magnetic field affects the properties of the SPPs for two branches.•Nonreciprocal effect is more obvious in the acoustic branch than in the optical one.•Critical chemical potential falls or even disappears as the wavelength gets longer.•External magnetic field prolongs the propagation length for the acoustic branch.

We study numerically the properties of surface plasmon-polaritons (SPPs) in a gyroelectric slab sandwiched between two graphene layers, where the external static magnetic field is applied in the Voigt geometry. It is shown that the dispersion characteristics and propagation lenghts of the SPPs for both the optical and the acoustic branches can be tuned flexibly by the external magnetic field and graphene's chemical potential, and that the nonreciprocal properties of the SPPs caused by the external magnetic field are rather obvious. The results provide a method for adjusting and improving the dispersion and propagation properties of the SPPs, which might be helpful for the design of the related plasmonic devices.