Oblique Klein tunneling in 8-Pmmn borophene p-n junctions

TL;DR

This paper analytically investigates oblique Klein tunneling in 8-Pmmn borophene p-n junctions, revealing how anisotropy and tilt cause perfect transmission to occur at oblique angles rather than normal, with potential experimental observability.

Contribution

It provides the first analytical study of oblique Klein tunneling in anisotropic and tilted Dirac fermion systems like borophene, identifying the junction direction dependence and the contributions of anisotropy and tilt.

Findings

Perfect transmission occurs at oblique angles due to anisotropy and tilt.

Oblique Klein tunneling is independent of doping levels.

A special junction direction maximizes the difference in transmission angle.

Abstract

The 8-\textit{Pmmn} borophene is one kind of new elemental monolayer, which hosts anisotropic and tilted massless Dirac fermions (MDF). The planar \textit{p-n} junction (PNJ) structure as the basic component of various novel devices based on the monolayer material has attracted increasing attention. Here, we analytically study the transport properties of anisotropic and tilted MDF across 8-\textit{Pmmn} borophene PNJ. Similar to the isotropic MDF across graphene junctions, perfect transmission exists but its direction departures the normal direction of borophene PNJ induced by the anisotropy and tilt, i.e., oblique Klein tunneling. The oblique Klein tunneling does not depend on the doping levels in \textit{N} and \textit{P} regions of PNJ as the normal Klein tunneling but depends on the junction direction. Furthermore, we analytically derive the special junction direction for the maximal difference between perfect transmission direction and the normal direction of PNJ and clearly distinguish the respective contribution of anisotropy and tilt underlying the oblique Klein tunneling. In light of the rapid advances of experimental technologies, we expect the oblique Klein tunneling to be observable in the near future.