Gate-Tunable Lifshitz Transition of Fermi Arcs and Its Transport Signatures

One hallmark of Weyl semimetals is the emergence of Fermi arcs(FAs)in surface Brillouin zones,where FAs connect the projected Weyl nodes of opposite chiralities.Unclosed FAs can give rise to various exotic effects that have attracted tremendous research interest.Configurations of 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 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 their configurations.We show that such an effect can be probed by the transport measurements in a magnetic field,in which the switch-on and switch-off conductances by the surface gate voltage signal 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.