Quantum confinement effect induced topological phase transitions in anisotropic Weyl semimetal

The quantum anomalous Hall effect can be realized in the Weyl semimetal based on a simple cubic lattice. On the basis of the system with broken time-reversal symmetry, we find the energy spectrum is isotropic in k_x and k_y direction but anisotropic in k_z direction. And the quantum confinement effect is strongly anisotropic in different direction, exhilaratingly, the periodic modulation of energy gap with the film thickness along z direction is found. We also find out that the topological phase transition is happened between a topological trivial insulator and a quantum anomalous Hall insulator due to confinement effect. These results can not only promote a better understanding of Weyl Semimetal, but also provide a good platform to design topological quantum devices based on the Weyl semimetal in the future.