  In this work, we theoretically investigate the superluminal and subluminal
reflected group delay from an air-Weyl semimetal film-Weyl semimetal substrate
layered structure by using 4*4 magneto-optical matrix. We show a tunable
transition between positive and negative group delays of reflection pulse in
such a layered structure controlled by the properties of the Weyl Semimetal
layer and reveal its mechanism to control the propagation properties of the
light pulse reflected from such structure. It is demonstrated that the
reflected group delays are tunable from positive to negative values and vice
versa, which are adjusted by tuning the incident angle, thickness of Weyl
semimetal film, tilt parameter, and Fermi energy. The control of the magnitude
and the sign of the reflected group delay of light propagation represent a key
point in slow and fast light technologies. Our results are helpful to control
the pulse propagations and are useful for design of Weyl semimetal-based delay
devices.
