  One hallmark of the Weyl semimetal is the emergence of Fermi arcs (FAs) in
the surface Brillouin zone that connect the projected Weyl nodes of opposite
chirality. The unclosed FAs can give rise to various exotic effects that have
attracted tremendous research interest. The configurations of the FAs are
usually thought to be determined fully by the band topology of the bulk states,
which seems impossible to manipulate. Here, we show that the FAs can be simply
modified by a surface gate voltage. Because the penetration length of the
surface states depends on the in-plane momentum, a surface gate voltage induces
an effective energy dispersion. As a result, a continuous deformation of the
surface band can be implemented by tuning the surface gate voltage. In
particular, as the saddle point of the surface band meets the Fermi energy, the
topological Lifshitz transition takes place for the FAs, during which the Weyl
nodes switch their partners connected by the FAs. Accordingly, the magnetic
Weyl orbits composed of the FAs on opposite surfaces and chiral Landau bands
inside the bulk change its configurations. We show that such an effect can be
probed by the nonlocal transport measurements in a magnetic field, in which the
switch on and off of the nonlocal conductance by the surface gate voltage
signals the Lifshitz transition. Our work opens a new route for manipulating
the FAs by surface gates and exploring novel transport phenomena associated
with the topological Lifshitz transition.
