Light-modulated electron retroreflection and Klein tunneling in a graphene-based n-p-n junction

We investigate the electron retroreflection and the Klein tunneling across a graphene-based n-p-n junction irradiated by linearly polarized off-resonant light with the polarization along the x direction.The linearly polarized off-resonant light modifies the band structure of graphene,which leads to the anisotropy of band structure.By adjusting the linearly polarized light and the direction of n-p-n junction simultaneously,the electron retroreflection appears and the anomalous Klein tunneling,the perfect transmission at a nonzero incident angle regardless of the width and height of potential barrier,happens,which arises from the fact that the light-induced anisotropic band structure changes the relation of wavevector and velocity of electron.Our finding provides an alternative and flexible method to modulate electron retroreflection and Klein tunneling.

Anisotropic refraction and valley-spin-dependent anomalous Klein tunneling in a 1T'-MoS_(2)-based p–n junction

We investigate the transport properties of electron in a 1T'-MoS_(2)-based p–n junction.The anisotropic refraction of electron is found when the electron beam crosses the p–n junction,which brings the phenomenon of valley splitting without any external fields.Moreover,it is found that the valley-spin-dependent anomalous Klein tunneling,i.e.,the perfect transmission exists at a nonzero incident angle of valley-spin-dependent electron,happens when the vertical electric field is equal to the critical electric field.These two peculiar properties arise from the same reason that the tilted band structure makes the directions of wavevector and velocity different.Our work designs a special valley splitter without any external fields and finds a new type of Klein tunneling.

On Klein tunneling of low-frequency elastic waves in hexagonal topological plates

Incident particles in the Klein tunnel phenomenon in quantum mechanics can pass a very high potential barrier.Introducing the concept of tunneling into the analysis of phononic crystals can broaden the application prospects.In this study,the structure of the unit cell is designed,and the low frequency(<1 k Hz)valley locked waveguide is realized through the creation of a phononic crystal plate with a topological phase transition interface.The defect immunity of the topological waveguide is verified,that is,the wave can propagate along the original path in the cases of impurities and disorder.Then,the tunneling phenomenon is introduced into the topological valley-locked waveguide to analyze the wave propagation,and its potential applications(such as signal separators and logic gates)are further explored by designing phononic crystal plates.This research has broad application prospects in information processing and vibration control,and potential applications in other directions are also worth exploring.