# Tilted Klein tunneling across atomically sharp interfaces

## TL;DR

This paper predicts a novel effect called tilted Klein tunneling caused by atomic-scale interfaces in graphene, which breaks the conventional Klein tunneling and impacts ballistic electronic device performance.

## Contribution

It introduces the concept of tilted Klein tunneling due to atomically sharp interfaces, a phenomenon not captured by continuum models, highlighting the importance of lattice effects in electronic transport.

## Key findings

- Breakdown of conventional Klein tunneling in graphene.
- Introduction of tilted Klein tunneling due to atomic interfaces.
- Relevance for high-density ballistic electronic devices.

## Abstract

Despite many similarities between electronics and optics, the hopping of the electron on a discrete atomic lattice gives rise to energy band nonparabolicity and anisotropy. The crucial influences of this effect on material properties and its incorporation into the continuum model have received widespread attention in the past half century. Here we predict the existence of a different effect due to the hopping of the electron across an atomically sharp interface. For a general lattice, its influence on transport could be equally important as the energy band nonparabolicity/anisotropy, but cannot be incorporated into the continuum model. On the honeycomb lattice of graphene, it leads to the breakdown of the conventional Klein tunneling -- one of the exotic phenomena of relativistic particles -- and the onset of tilted Klein tunneling. This works identifies a unique feature of the discrete atomic lattice for transport, which is relevant for ballistic electronic devices at high carrier densities.