Strain-Controlled Anisotropic Pseudospin Tunneling in the α-T3 Model

We investigate the anisotropic pseudospin tunneling effect of electrons through a potential barrier in the alpha-T-3 model under an uni-axial strain. When compressing the alpha-T-3 lattice along the armchair direction, a pair of Dirac points in the energy band structure may merge into a single one along the zigzag direction. If the strain is strong enough, the energy gap will open, and the dispersion relation will be linear in the armchair direction but quadratic in the zigzag direction. The merging of Dirac points represents a topological phase transition from a metallic phase to an insulating phase. We found that in the armchair direction, the tunneling properties are similar to the undeformed alpha-T-3 lattice. For example, when the incident particle is normal to the potential barrier, we find Klein tunneling effect independent of alpha, and for the dice lattice with the incident energy is equal to half of the barrier height, there occurs super-Klein tunneling. While in the zigzag direction, we get the opposite conclusion in the deformed alpha-T-3 lattice. The Klein tunneling effect becomes the reflection effect, and the super-Klein tunneling effect is transformed into the total reflection effect, and the conductance with gap opening can be turned off using strain applied along the armchair direction.