Edge photocurrent in bilayer graphene due to inter-Landau-level transitions

TL;DR

This paper demonstrates the resonant excitation of edge photocurrents in bilayer graphene induced by terahertz radiation and magnetic fields, revealing both classical and quantum Landau level transition effects.

Contribution

It provides experimental evidence of both intra-band and inter-band Landau level transitions causing edge photocurrents, supported by semiclassical theory and detailed spectral analysis.

Findings

Resonant edge photocurrents observed at Landau level transitions

Intra-band transitions linked to classical cyclotron resonance

Inter-band transitions exhibit quantum features and weaker signals

Abstract

We report the observation of the resonant excitation of edge photocurrents in bilayer graphene subjected to terahertz radiation and a magnetic field. The resonantly excited edge photocurrent is observed for both inter-band (at low carrier densities) and intra-band (at high densities) transitions between Landau levels (LL). While the intra-band LL transitions can be traced to the classical cyclotron resonance (CR) and produce strong resonant features, the inter-band-LL resonances have quantum nature and lead to the weaker features in the measured photocurrent spectra. The magnitude and polarization properties of the observed features agree with the semiclassical theory of the intra-band edge photogalvanic effect, including its Shubnikov-de-Haas oscillations at low temperatures.