Anomalous Klein paradox due to misalignment of optically-tunable elliptical dispersion for Dirac-cone dressed states and direction of incoming particles

TL;DR

This paper reveals an anomalous Klein paradox caused by misaligned elliptical dispersion in Dirac materials under optical dressing, affecting electron tunneling and transmission properties, with potential applications in nano-scale electronic devices.

Contribution

It introduces the concept of anomalous Klein paradox due to optical control of elliptical dispersion in Dirac materials, expanding understanding of electron tunneling under high-frequency dressing fields.

Findings

Anomalous Klein paradox occurs at nonzero incident angles.

Larger off-peak transmission in dice lattices compared to graphene.

Transmission depends on light polarization, anisotropy, and electron-light coupling.

Abstract

After having derived boundary conditions for dressed-state electrons in a dice lattice, we investigate the electron tunneling through a square electrostatic potential barrier in both dice lattices and graphene under a linearly-polarized off-resonance and high-frequency dressing field, and demonstrate the anomalous Klein paradox for a nonzero incident angle, resulted from the misalignment of optically-controllable elliptical dispersion for Dirac-cone dressed states and the direction of incoming kinetic particles in our system. This finite incident angle is found depending on the type of light polarization, the light-induced anisotropy in energy dispersion and the strength of electron-light coupling. Meanwhile, we also observe much larger off-peak transmission amplitudes in dice lattices in comparison with graphene. We expect the theoretical results in this paper could be used for wide range of Dirac materials and applied to controlling both coherent tunneling and ballistic transport of electrons for constructing novel optical and electronic nano-scale switching devices.