  The Imbert-Fedorov (IF) shift in optics describes the transverse shift of
light beams at the reflection interface. Recently, the IF shift of Weyl
fermions at the interface between Weyl semimetals (WSMs) with single monopole
charge has been studied. Here, we study the IF shift at the interface between
two WSMs, each of which is carrying an arbitrary integer monopole charge. We
find a general relation between the monopole charges of the two WSMs and the IF
shift. In particular, the IF shift is proportional to the monopole charge if
both WSMs have the same one. Our results can be used to infer the topology of
the materials by experimentally measuring their IF shift. Furthermore, we
consider the possibility that the Weyl fermions are scattered to other Weyl
cones during the reflection, which results in qualitatively different behavior
of the IF shift. While we use a quantum mechanical approach to solve the
problem, semiclassical equations of motion and the conservation of total
angular momentum can help us intuitively interpret our results in special
cases.
