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

Abstract

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.

Transport and confinement in bilayer chiral borophene

“…In general, the transmission fringes, which are more eminent for ∆ = 0, are a manifestation of Fabry-Pérot resonances and arise from the finite width of the barrier. Remarkably, they perfectly connect to the bound states (black bands in figure 4), which are the solutions of equation (20) for ∆ = 0 and equation (22) for ∆ ̸ = 0. The reason for the connection is that the Fabry-Pérot resonances and bound states arise from the same standing wave condition.…”

“…We calculate E and k y for a bound state either from equation (20) or from equation (22), and evaluate M α . Then, we calculate C s 8 as the null space of M α and utilize it to find P α,i (x).…”

“…The transport in the predicted 8-Pmmn phase was the topic of several works highlighting the phenomenon of oblique Klein tunneling, which arises from tilted and anisotropic Dirac cones. These studies were carried out for n-p [19] and n-p-n [20,21] junctions with additional consideration of hydrogenation (borophane). Common features of interest were the anisotropy and the directional dependence of the electronic properties.…”

Light-modulated graphene-based φ 0 Josephson junction and −φ 0 to φ 0 transition

“…[2] By using the tight-binding model, there are two inequivalent corners K and K ′ in the first Brillouin zone, around which is a conical band structure described by the massless Dirac equation. [3] Owing to its linear electronic spectrum, graphene has become a new type of "relativistic" material, where some unobservable relativistic phenomena in high energy physics, such as Klein tunneling and anomalous Klein tunneling, [4][5][6][7][8] can be easily mimicked and tested in condensed matter physics. Graphene not only provides a highly practical and prospective platform for studying fundamental physics, such as half-integer quantum Hall effect, [9] specular Andreev reflection, [10] topological phase transition, [11][12][13][14] and superconductivity, [15][16][17][18] but also has extraordinary applications in future, such as next-generation electronics and photonics, [19,20] device physics, [21] and heterostructure.…”

Anisotropic and valley-resolved beam-splitter based on a tilted Dirac system

“…Some unusual electronic and transport properties caused by the tilt of the Dirac cone have been demonstrated theoretically, such as strongly anisotropic plasmon [29] and optical conductivities [30], unique intervalley damping effect in magnetoplasmons [31], valley-dependent Weiss oscillation [32], nearly perfect valley polarization induced by a single ferromagnetic gate [33], and light-driven metal-insulator transition [34,35]. Electron optics based on tilted Dirac systems has been discussed in several works [33,36,37] which concern valleydependent electron retroreflection, oblique Klein tunneling, generalized Klein tunneling, and Veselago focusing. The GH shift in tilted Dirac systems has not been studied so far.…”