  Surface plasmon polaritons in a strained slab of a Weyl semimetal with broken
time-reversal symmetry are investigated. It is found that the strain-induced
axial gauge field reduces frequencies of these collective modes for
intermediate values of the wave vector. Depending on the relative orientation
of the separation of Weyl nodes in momentum space, the surface normal, and the
direction of propagation, the dispersion relation of surface plasmon polaritons
could be nonreciprocal even in a thin slab. In addition, strain-induced axial
gauge fields can significantly affect the localization properties of the
collective modes. These effects allow for an in situ control of the propagation
of surface plasmon polaritons in Weyl semimetals and might be useful for
creating nonreciprocal devices.
