Magnetic-field-controlled negative differential conductance in graphene npn junction resonators

TL;DR

This paper demonstrates how magnetic fields can control negative differential conductance in graphene npn junction resonators, enabling on/off switching and tuning of NDC regions via Landau level manipulation.

Contribution

It introduces a novel method to control NDC in graphene devices using magnetic fields, leveraging Landau level shifts and Klein tunneling effects.

Findings

Magnetic fields can switch NDC on and off in graphene npn junctions.

Landau levels in graphene are shifted by magnetic fields and tip-induced effects.

Tunneling between misaligned Landau levels causes magnetic-field-controlled NDC.

Abstract

Negative differential conductance (NDC), characterized by the decreasing current with increasing voltage, has attracted continuous attention for its various novel applications. The NDC typically exists in a certain range of bias voltages for a selected system and controlling the regions of NDC in curves of current versus voltage (I-V) is experimentally challenging. Here, we demonstrate an unusual magnetic-field-controlled NDC in graphene npn junction resonators. The magnetic field not only can switch on and off the NDC, but also can continuously tune the regions of the NDC in the I-V curves. In the graphene npn junction resonators, magnetic fields generate sharp and pronounced Landau-level peaks with the help of the Klein tunneling of massless Dirac fermions. A tip of scanning tunneling microscope induces a relatively shift of the Landau levels in graphene beneath the tip. Tunneling between the misaligned Landau levels results in the magnetic-field-controlled NDC that may have potential applications for future graphene-based technology.