Coupling between a Weyl semimetal and a nontopological metal

We study the effects of tunneling between a Weyl semimetal (WSM) and a simple parabolic band. When coupled to the nonmagnetic parabolic band, the interface between the two exhibits two main phenomena. First, the WSM's chiral arc state lowers in energy, and second, a previously extended WSM state becomes localized to the interface and is lowered in energy. Together these surface bound states create a new closed orbit in momentum space, and a noticeable spin-dependent asymmetry in the interface spectrum in the vicinity of the Weyl nodes appears. We study these effects with a lattice model that we solve numerically on a finite sample and analytically using an Ansatz on an infinite sample. Our Ansatz agrees very well with the numerical simulation as it accurately describes the behavior of the chiral state, from its energy asymmetry to the spin rotation at the interface. We find that the tunneling effectively increases the Fermi arc length, allowing for the presence of interface states beyond the bare Weyl nodes. These additional states may carry current along the interface, and their contribution can be detected in the conductance. In addition to conductivity, the effect of tunneling between the WSM and the metal can be seen in quantum oscillation experiments, which we briefly address.